"I get called fat all the time. A big fat whore," she told the mag.
"Lady Gaga's fans are the worst," she continued. "They've said I should kill myself, that they hope I get raped. I mean, it's crazy but I've had this all my life and I just try and ignore it."
Gaga's 'Little Monsters' were particularly incensed when Kelly made catty comments about Gaga on her US fashion TV show - including calling the pop star "disrespectful" for not walking the 2012 Grammy Red Carpet.
Kelly also chimed in on Gaga's much talked-about weight gain last year. She mused during a TV interview that the singer might be pregnant.
Speaking to Channel 4's Alan Carr, Kelly, who was asked to comment on a snap of Gaga wearing a burka, said: "I think she is pregnant because she has been covering up this part of her body recently and I have been noticing that a lot.
"And her style has changed and you can't bleach your hair blonde when you are pregnant.
"I have no filter," Osbourne said. "I say what I think and that's it. I actually think she's a good singer but she has the worst fans in the world and you have a responsibility to stop that. I think you do anyway."
Check out Kelly's appearance on the show below:
As noted above, Sharon got stuck into the saga late last week and emailed Gaga's manager to see if her fans would cut Kelly some slack.
'NOTHING MORE THAN A PUBLICLY SEEKING HYPOCRITE...'
Sharon went on to call Gaga's letter "hypocritical and full of contradictions", noting that just as Gaga's mother Cynthia supports her, so does she support her daughter.
"How sweet that you have empathy for my daughter, as you feel that she has taken a less passionate path in life. You say her work on E! with the Fashion Police is 'rooted in criticism, judgment, and rating people's beauty against one another.' Welcome to the real world.
"Example, when I saw you wear a dress made out of raw meat, I was sickened. When I see you wearing fur, and using it as a fashion statement, the fact that defenseless animals have been killed so you can get your picture in the press is abhorrent to me. Shouldn't you be teaching your 'little monster' fans to respect animals and life?"
Sharon, 60, then added: "By your actions to Kelly right now, you have shown me that you are nothing more than a publicly seeking hypocrite and an attention seeker.
"You know it would have been much more dignified of you to do this privately. I am calling you a bully because you have 32 million followers hanging on your every word and you are criticising Kelly in your open letter. Are you so desperate that you needed to make this public?"
And she didn't stop there.
"I don't know what world you live in, but supporting disgraceful fan comments doesn't fall under the words 'kinder and braver.' It comes under the heading of bullshit."
She concluded: "In closing, stop wearing fur, stop looking for publicity, and stop using your fans to belittle not just Kelly but an endless stream of celebrities. A word from you would stop all the hideous, negative and vile threats from your 'little monsters.'
"Let me know if you want to continue this debate. I'm an open playing field for you my darling."
Kelly then chipped in, tweeting: "I hope you guys realise that I don't care about any of this bullshit! I know who I am I don't need anyone to tell me!...love to all."
'FOR GOD'S SAKE, CALM DOWN'
Osbourne's Fashion Police co-star, Joan Rivers, also chimed. "Fashion Police is a comedy show; anyone that comes out of an egg should figure that out," she told Entertainment Tonight.
The scalpel-tongued legend also told The Huffington Post that Gaga should "calm down".
"I think this will hurt Gaga a little in the long term. It's brought up again the fact she loves animals and wears fur," she told the website.
"'Fashion Police is funny. Gaga, of all people, should know that. She worked the same little clubs I did in the Village. She has gay followers and she doesn't know funny? For God's sake, calm down. I think that Gaga, who is making hundreds of millions of dollars a year, with a bad nose, should get on her knees and thank God."
In her post to Kelly, Gaga, who is the founder of the Born This Way Foundation against bullying, had asked her to "take responsibility and accountability" for the example she is setting for her fans.
"While I wish you had reached out to me personally, as the head of the Born This Way foundation with my mother Cynthia, we would like to respond," Gaga began. "Everyday, through my music and public voice I choose to be positive and work towards a kinder and braver world with our community of followers."
She then pointed the finger at Kelly's Fashion Police hosting gig.
"I have empathy for you Kelly, but I feel it culturally important to note that you have chosen a less compassionate path. Your work on E! with the Fashion Police is rooted in criticism, judgment, and rating people's beauty against one another," she wrote.
"'Appearance' is the most used reason for bullying in the world. Your show breeds negativity, and over the years has even become comedic in nature. It glorifies you and Joan Rivers pointing in the camera, laughing, and making jokes about artists and celebrities as if we are zoo animals. What about your body revolution?
"It used to make me truly sad when I would hear people talk about your weight when you were younger, as I was bullied too. To see you blossoming into a beautiful slender woman who makes fun of others for a living is astounding. Why not help others? Why not defend others who are bullied for their image and share your story?"
And the saga continues.
Gaga later took to her Facebook page on Sunday to defend her statements.
"The 'real world' can be cruel, why not try to change it into a better place?" Gaga wrote. "I am an activist. Nobody takes adolescents seriously, I do. My letter to Kelly Osbourne was open, because her statements on cyber-bullying were public & as a youth activist I'm compelled to be involved."
Your move, Osbournes...
FAST GOSSIP
And finally...
* Kylie Minogue to quit music for acting, says a so-called 'source' close to singer.
* Britney Spears returns $90,000 engagement ring to Jason Trawick after split. TMZ claims they broke up over kids.
* Evan Rachel Wood and Billy Elliot star Jamie Bell expecting first baby.
* Olivia Wilde and comedian boyfriend Jason Sudeikis are engaged!
* Demi Moore dating Lindsay Lohan's ex? Cobblers.
* Jurassic Park 4 gets release date.
* Tina Fey thinks most people are too boring to use Twitter.
* "I'm shutting your butt down" - Quentin Tarantino refuses to talk violence with TV interviewer.
* "I'm ready" - Justin Timberlake returns to music.
* Listen: Destiny's Child debut their brand new song Nuclear...
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