By Alexis Tereszcuk, 
 
 Senior Radar Reporter 
 
 Ashton Kutcher’s cheating on his wife was the straw that broke the camel’s back but it was the “open marriage” they had that was the downfall in their marriage. 
 
 Demi Moore, 49, is filing for divorce from her 33-year-old husband after his latest affair became public, and Star magazine has exclusively learned that her secret life with Ashton and their “open marriage” has been much more twisted than anyone imagined. 
 
 “Everyone in Hollywood knows about their arrangement, but they’ve managed to keep it a secret from the general public,” an insider said about the A-list couple. 
 
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 “Demi is attracted to women just as much as men, so she didn’t always get all she needed from Ashton.” 
 
 Apparently they were happy with the arrangement they had for a while. “She was cool with Ashton having flirtatious relationships too. Somehow they made it work all these years. Both of them were respectful of each other,” the source said. “It was a lot of fun for them.” 
 
 But it all changed when Ashton’s affairs became public, first in 2010 when Star exclusively reported that he had a fling with 21-year-old Brittney Jones and then his one night stand with Sara Leal on his sixth wedding anniversary. 
 
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 So Demi finally decided to take matters into her own hands and end the marriage, announcing Thursday that she was going to divorce her philandering husband. 
 
 “It is with great sadness and a heavy heart that I have decided to end my six-year marriage to Ashton. As a woman, a mother and a wife there are certain values and vows that I hold sacred, and it is in this spirit that I have chosen to move forward with my life,” Demi said. 
 
 For more details about Ashton and Demi’s “open marriage” arrangement pick up the current issue of Star magazine on newsstands now. 
 
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 Ashton's Alleged Mistress Now Do You Believe Me?!!?! 
 
 's alleged mistress -- the FIRST alleged mistress -- claims she feels "vindicated" by's divorce statement ... telling TMZ she hopes people will finally believe her story about sleeping with Ashton.TMZ spoke with-- who claimed she got busy with Kutcher in 2010 after meeting the guy at a bowling alley. Jones' credibility was called into question when she capitalized on her sudden fame by releasing a sex tape .... which did NOT feature Ashton.Ashton's lawyer released a statement at the time Brittney was in the headlines, insinuating her story was a lie ... but not entirely denyingNow, Jones tells TMZ ... "Although divorce is often sad I do feel somewhat vindicated."She adds, "For so long people have thought that I was dishonest or just making up my passionate nights with Ashton, when in fact I was being used.""Ashton told me that both he and Demi had an 'open relationship' and that he was not in fact cheating. Now I can tell all the facts about how Ashton really was, and hopefully people will believe my side of the story."Still, Jones says, "I feel for Demi very much and wish her nothing but the best during this hard time."
– Now that Demi Moore and Ashton Kutcher have announced their split, the deluge of “What went wrong?” stories can come rushing in. According to a Star story cited by Radar, it all comes down to the couple’s open marriage (a rumor we’ve heard before). "Everyone in Hollywood knows about their arrangement, but they’ve managed to keep it a secret from the general public," says a source, adding that the couple used to be happy with the arrangement and had "a lot of fun." So what went wrong? "Demi is attracted to women just as much as men, so she didn’t always get all she needed from Ashton," the source says. Meanwhile, Kutcher’s alleged mistress is having her “I told you so” moment. No, not the mistress from the latest cheating scandal; the one from last year who tried to sell Kutcher’s morning-after sweater. She tells TMZ, "Although divorce is often sad I do feel somewhat vindicated," since many people doubted her story. Demi will surely be happy to hear that the other woman wishes her "nothing but the best during this hard time." Click for Demi and Ashton’s statements on the split.