Ms Desporte told the Sunday Mirror about how Mr Bull from Mansfield, Nottinghamshire, wooed her during a boozy night at her bar on the Spanish island.
The bar owner, originally from Bournemouth, told the paper: "I was chatting to his mate and he came over and said, 'Come and talk to me, I'm interesting, I've won the Lottery'.
Those were his exact words.
"I laughed at him and said, 'We get a lot of fruitcakes in this bar and you're obviously another one of them'."
But he said, "No, Google me, Google me". So I looked on my phone and it was true. Gareth told me he was still married, but they had split up.
Mr Bull, a self-employed builder, bought the lottery ticket in 2012 on a whim after he was unable to work one day because it was raining.
He only realised the following morning that he and his wife had hit the jackpot.
Mrs Bull - who worked in health insurance at the time of the win - said they were so shocked they took days to reveal their news to their sons Joel, then ten, and Declan, then nine.
Incredibly, the couple carried on with their weekend plans as normal, taking the boys to play in football matches and hosting a birthday sleepover.
Mr Bull built his family's six bedroom, six bathroom house in Mansfield himself.
The couple said it was already their 'dream home' and they did not want to move - although they did buy a holiday villa in Tenerife.
But the curse of the jackpot struck the family, and it was reported in April this year that Mr Bull had moved to a three-bedroom cottage just over a mile away from the family home.
A source told The Sun: "The marriage has been doomed for some time.
"To be fair, it wasn't the greatest when they hit the jackpot. They felt the massive win may help improve matters. But the curse of the Lottery has struck yet again."
And now Ms Desporte has come forward to voice her anger as Mr Bull denied their relationship - which she said was ongoing while the married couple had a two-year
separation.
She said: "He told her we were just friends and there was no sex. He's not talking to me now. And I'm furious."
Mr Bull has been contacted for comment by MailOnline.
Marriages ended by money
The Bull's split follows a pattern similar to so many lottery-winning couples before them.
They include Les and Samantha Scadding, who scooped £45.5million (NZD $79million) in 2009, and divorced in 2013, and Adrian and Gillian Bayford, who won £148million (NZD $260million) in 2012, and split just a year later.
Jason and Victoria Jones had been married for only a month when they scooped £2.3million (NZD $4million) on the lottery in 2004.
But the pair announced they were to divorce in August last year after Mrs Jones met a businessman one hundred times richer than her husband.
