Country superstar Trace Adkins’ $20 million divorce was trig­gered by the serial cheater’s boasting about his countless female conquests, his out-of-control drinking and his “fantasy” love affair with a sexy Canadian actress!

A source tells The ENQUIRER that a series of steamy tweets about Trace from his sultry film co-star Victoria Pratt really infuriated his long-suffering wife Rhonda. And that, along with his badboy behavior, led her to pull the plug on their 16-year marriage.

But now the hulking country crooner – whose secret, twisted life was exposed in a bombshell ENQUIRER exclusive – is struggling to save his tattered marriage.

“Trace desperately wants to get back with Rhonda,” a source told The ENQUIRER. “He’s quit drinking, he’s attending AA meetings and he’s telling friends that all he wants is to get his family back together. But it’s too late. Rhonda is fed up, and their marriage is history!”

As The ENQUIRER recently revealed, 50-year-old Rhonda began pressuring Trace, 52, for a divorce after he confessed that he’d flipped for married actress Victo­ria, 43. And when Victoria posted several raunchy tweets while filming the west­ern movie “The Virginian” with Trace, sources say Rhonda hit the roof. In one tweet, Victoria wrote: “Gave Trace Adkins a sponge bath at work today…just another day at the office. I owe the universe big time!”

Victoria went on to wisecrack: “I’m afraid I didn’t get to everything. So ashamed!”

Finally, on March 24, beleaguered third wife Rhonda slapped Trace with a divorce suit in Franklin, Tenn. “Rhonda has been asking Trace for a mutual divorce for some time, but he would never agree,” said the source. “Finally, she filed on her own.”

Rhonda claimed in her divorce papers that the pair separated on March 24. But as we revealed, she booted Trace out of the Nashville-area home they shared with their three daughters months ago, and he moved into a guest cottage on another property.

The singer made national headlines earlier this year when he got into a drunken confrontation with a look-alike impersonator during a country-themed cruise.

 While Trace claimed to have been sober for 12 years, The ENQUIRER learned that he’d fallen off the wagon more than a year ago.

The hot-headed horndog also bragged to a friend that he cheat­ed on Rhonda with nearly a dozen women during their marriage – even crowing that he’d had sex with two other women in one day, before returning home and bedding Rhonda. He also boasted that while they competed on TV’s “Celebrity Apprentice,” Oma­rosa Manigault offered him sex “at least a hundred times” and supermodel Carol Alt proposi­tioned him.

“Rhonda was totally humiliated,” an insider told The ENQUIRER. “When Trace told her that he had fallen in love with Victoria Pratt, she completely flipped out. Victoria became Trace’s fantasy sex partner, and he talked constantly about how much he loved her. Adding insult to injury, Rhonda was told that Trace would compare his sexual experi­ences with her to fantasies of what it would be like with Victoria!”

Victoria is married to T.J. Scott, a Hollywood director and photographer. But The ENQUIRER has learned that she and Trace attended the Stagecoach Festival in Indio, Calif., where Trace performed, and then hung out together after­ward. When The ENQUIRER contacted Victoria by phone, she hung up as soon as Trace’s name was mentioned.

Meanwhile, a source says Trace’s “friends” have been giving Rhonda the scoop on his bad-boy shenanigans.

“Rhonda has put up with Trace’s cheating and abuse for years,” said the source. “But now she knows everything he’s done, and she plans to use it to make him pay big-time.”