COUNTRY star JASON ALDEAN’s cheatin’ heart has landed him in the middle of a $20 million divorce war!

The “My Kinda Party” singer, who filed for divorce from his wife of nearly 12 years, Jessica Ussery, on April 26, had been treading on thin ice ever since he was caught kissing former “American Idol” contestant Brittany Kerr at a Hollywood bar in September.

The couple reportedly tried to patch things up, but the relationship completely collapsed once Jessica learned the full scope of her hubby’s wandering eye, say sources.

“Jessica found out that wasn’t the first time Jason had flirted with other women, it was just the first time he got caught,” a source explained. “She started getting reports from all over that when Jason was out touring, he was acting like a single guy.

AS HE RACKED UP the hit songs, his tours got bigger and bigger. He had girls chasing him, and he couldn’t resist temptation.

“His head was getting too big to fit into that trademark straw hat he wears – and now he’s going to have to pay for it in divorce court.”

Jason and Jessica began dating when they were 16 in their hometown of Macon, Ga., and she followed him to Nashville so he could pursue his music dreams. They married in 2001 and have two daughters, Keeley, 10, and Kendyl, 5.

“Jason didn’t get a lot of breaks early on,” a friend said. “He kicked around Nashville for a long time before becoming a star.”

Finally, seven years after arriving in Music City, Jason’s luck began to change. Since the release of his debut album in 2005, he’s scored 11 No. 1 country singles. And thanks to the success of such hits as “She’s Country,” “Big Green Tractor” and “Take a Little Ride,” the 36-year-old is now performing to sell-out crowds at such esteemed – and decidedly “uncountry” – venues as Boston’s Fenway Park and New York City’s Madison Square Garden. He’s also amassed an estimated $20 million fortune – and Jessica is entitled to a big chunk of it.

“She can show she was instrumental in Jason achieving success, but even more, she can show she is the wronged party in this,” the source noted.

Despite an attempt to keep the marriage together in the wake of the embarrassing Brittany Kerr incident, the friend says Jessica was overwhelmed by the rampant rumors of other flings. When Jason headed out in February for his 2013 national tour, which runs through October, Jessica stayed home.

“SHE’D HAD ENOUGH,” said the friend. “It’s heartbreaking for her because she stood by him when nobody knew who he was.”

The other source added: “I do think Jason feels badly about their split, especially with two young daughters at home.

“He’s going to give Jessica whatever she asks just so he doesn’t have to deal with having his dirty laundry dragged out for everyone to see.”