He is set to make explosive allegations about his wife's sexual preferences. Last night, a friend of Belafonte said: "By the sounds of it, things are about to turn incredibly nasty between Mel and Stephen.
"He wants his day in court. Stephen insists all their sexual exploits and threesomes were completely consensual and sometimes even instigated by Melanie."
Together, the couple have a daughter, Madison, five, while Mel has two daughters, Angel, ten, from her previous relationship with actor Eddie Murphy, and Phoenix, 18, from her first marriage to former dancer Jimmy Gulzar.
Belafonte has also told friends the couple originally agreed to divorce amicably to protect the children. Sadly, it seems there is little chance of that now. News of Belafonte's fight-back comes as sources also disclose that Mel's UK relatives have long had worries about the marriage -with particular concern for "what it was doing to the children".
Their fears reached fever-pitch when, the source says: "They heard stories about all sorts of things going on with Mel and Stephen, including sex parties, and they wanted to get Phoenix out of there."
Last summer, in the midst of talks about another Spice Girls reunion, Mel's former bandmate Geri Horner was so worried that she offered for Mel and her family to come to live with her in London.
A source close to Mel says: "Both Geri and former Spice Girl Emma Bunton were very concerned about Mel, her state of mind, when they spent time with her. It was obvious things had gone badly wrong between her and Stephen." So who's the real guilty party?
Just six weeks after giving birth to Angel in April 2007, Mel was dating Belafonte. Belafonte, now 41, was a film producer, who claimed (erroneously) to be related to legendary singer Harry Belafonte. Within weeks, he had married Mel.
Mel now explains her behaviour in court papers filed this week, which sought a restraining order against Belafonte, saying: "At the time of our marriage in June 2007 I was exactly two months from the birth of my second child.
"At the time I was vulnerable. I was giving birth as a single mother, my self-esteem was very low and my hormones were way out of balance due to the pregnancy.
"Respondent [Belafonte] rushed in to help me in every way...
"However... he became controlling, manipulative and abusive. He proposed to me after a very short relationship. In hindsight I believe this kindness was in essence his way of 'grooming' me given his recognition of my vulnerability stemming from my recent pregnancy."
It soon came to light that Belafonte hadn't declared his previous marriage to a woman known only as Nancy, who had the marriage annulled after less than 12 weeks amid claims he had been "emotionally abusive".
A criminal conviction also emerged. In 2003, Belafonte was convicted for battering his former partner Nicole Contreras, mother of his young daughter. He was spared jail after taking part in a "Domestic Violence Batterers' Programme".
When these details came to light, Mel defended her husband, claiming the conviction was a misunderstanding. She said: "Everything I stand for is about being a strong, independent woman, so for him to be seen as a wife beater is devastating for me because he's not - he never has been."
In court documents this week, though, she wrote that she had been deceived. "At the time of our marriage I was unaware that Belafonte was not the Respondent's legal surname, nor was I aware that he had been previously married."
Regardless, Belafonte, it seems, quickly got to work - and arranged a vow renewal ceremony in Egypt in 2008, sponsored by OK! Magazine to attract maximum revenue.
But all was reportedly not well behind the scenes - and, according to Mel, her husband began blackmailing her to have threesomes with other women.
Mel said: "When I threatened to leave, Respondent [Belafonte] informed me that he has videos of our sex life and other private moments... I have lived the past decade in fear that Respondent would release intimate videos of me that would embarrass me and damage my reputation and my career. Once Respondent made the threat of releasing videos it became impossible to say no to him, giving him complete control.
"Respondent often times demanded that I participate in sexual intercourse with him and random women that he brought back to our hotel rooms. If I objected to participating, he would threaten to release compromising videos of me."
Other debauched sex reportedly took place in the Playboy Mansion, with Belafonte apparently "badgering" Mel to have threesomes there.
In a therapy session filmed for Mel's 2010 reality TV show, It's A Scary World, Belafonte said: "I'm a super freak, I need to have certain amounts of sex," adding that withholding dalliances was equivalent to "taking my food and water away from me".
Such a relationship is at odds with Mel's image of a strong, independent female.
Previously, she has been frank about her love life, stating: "People call me lesbian, bisexual or heterosexual, but I know who's in my bed and that's it . . . I have a huge libido and a great sex life."
Lady Victoria Hervey is one reported lover of both Mel and Belafonte. Both Belafonte's brother, Jeremiah Stansbury, and Mel's ex husband Jimmy claim the couple were "obsessed" with porn. Others say theirs was an open marriage.
Such a woman, you might imagine, would not let a man humiliate her. Yet Belafonte reportedly did just that. After he hired their German nanny, Mel claims he "would degrade me in front of her... telling me how much younger and better looking she was. I later discovered that Respondent was having sex with Lorraine and was paying her inordinate amounts of money."
After the apparent shock of the nanny's reported pregnancy, Mel then claimed Belafonte "used money earned by me to pay for Lorraine's abortion, and he used money earned by me to pay for Lorraine's hotel stay while she recuperated from the procedure."
Mel also says Belafonte would regularly call her a "f***ing monkey", "stupid", "fat ugly and old", "dumb" and a "derelict".
One can only wonder how Mel - a self-made woman with a £40 million fortune, and a successful career as a pop star and television presenter of The X Factor and America's Got Talent - can have borne such treatment for so long.
Indeed, she seems to have been brought so low that death appeared to be the only escape.
When she took an overdose of aspirin after being abused by him in 2014 while filming for The X Factor, shockingly, she claims Belafonte turned away an ambulance, locked her in a bathroom and told her "die, bitch".
When her driver came the next morning, he took her to hospital rather than to the studios.
"I was badly hurt," she said. "I had security standing outside my hospital door with a picture of [Belafonte] so they knew to keep him out." Those heady days of Girl Power, of being a woman so in control, seem so far away.
As well as strongly denying all Mel's accusations, Belafonte says it is he, not she, who is the wronged party in their marriage.
As well as an affair with their nanny, he claims Mel had flings with other men behind his back, including one with a well-known, married British actor.
The Hollywood source also says he will claim in court some of their more vicious arguments stemmed from her excessive drinking.
A LOOMING BATTLE FOR HER FORTUNE
While the pair did not sign a pre-nuptial agreement prior to their marriage, a Hollywood source said yesterday: "Stephen says all he wanted was a quick, amicable divorce and that they had originally agreed he would get around £10,000 a month plus half the proceeds from the sale of their house which is standard practice under Californian law."
'Just' £10,000 a month would sound like a good living to many. As reported yesterday, Mel filed her divorce papers in the nick of time - just 11 weeks before their tenth wedding anniversary, after which date she would have been required by law to pay him spousal support in perpetuity.
She is now likely to only have to pay him for half the length of their marriage.
Indeed, she's already drawn attention to money being a contentious issue, claiming he paid $325,000 of her money without her consent to support his child by his ex partner.
Mel claims she asked her accountants to require her say-so for spending over $5,000 - only to apparently later learn Belafonte used her email account to review and approve his expenditure requests.
A FAMILY BEING TORN APART
Mel's mother Andrea was dismayed when she heard her daughter had married Belafonte in 2007. She said: "I think she's made a big mistake. How can you fall in love that quick?"
Both Andrea and Mel's sister Danielle attended the couple's vow renewal in Egypt. But during that four-day celebration, they fell out with Belafonte, whom they found intimidating.
By the following year, relations had deteriorated. Andrea and Danielle even backed Mel's first husband Jimmy Gulzar in one of many suits filed by him when seeking access to daughter Phoenix.
When Danielle flew out to Los Angeles in 2009 to try to talk to Mel about Belafonte, Mel refused to even meet her and told her she was just jealous and to "butt out and mind your own business".
Even a serious family illness didn't reunite them. In 2011, Danielle's son Hendrix was desperately ill in a London hospital, but there was still no contact from her sister. Then 16 months old, he was battling Kawasaki syndrome, a rare illness that attacks the immune system. His life was saved by blood transfusions.
Danielle said: "It sounds terrible, but... it would feel better thinking that maybe Mel is mentally unwell in some way. I'd like to think there was an excuse, a valid excuse for why she has cut off her entire family through all of this pain. That would be almost forgivable...
"I thought [Hendrix] was dying and I never got a phone call."
Then, last month, it was reported Mel's feud with her family was over. She invited them to Los Angeles, spurred to do so by the death of her father, Martin, earlier this year, and the reported behaviour of Belafonte at the time.
In her court filing, Mel says Belafonte told her to "suck it up. If he's going to die, he's going to die".
She also believes he took her passport to delay her return to the UK. She arrived in Leeds on February 28. Her father died on March 4. "After my father's passing I made the decision to separate and divorce Respondent... Respondent again threatened that if I did not separate in a manner acceptable to him, he would ruin me by releasing videotapes he claims to have made of me."
Mel also claims Belafonte insisted on coming with her to Spice Girls meetings last year about a possible reunion. "While I was there Respondent became angry and began screaming at me. He... threatened to send the other Spice Girls compromising videos of me."
This wasn't the first time Belafonte reportedly humiliated her while she was working. She claims he physically attacked her in November 2007 after she had been on the Dancing With The Stars finals and said: "I would come to realise that Respondent's beatings and abuse would coincide with my career success. When something good would happen for me, he would beat me down to let me know that he was in charge."
Another reported attack came in 2012 after recording for the X Factor in Sydney and, later that same year, Mel says he "punched her in the face with a closed fist" after the Spice Girls performance at the Olympics closing ceremony.
But it was while filming X Factor in London in 2014, she says, that the abuse became "overwhelming."
When Mel eventually appeared on television, her injuries "could not be concealed, even with heavy theatrical make-up."
Simon Cowell introduced her to divorce lawyers - yet she still did not move against her husband.
As this week's explosive allegations have shown, the gloves are finally off.
