EXCLUSIVE: Busted! Jennifer Aniston Cheated On Brad Pitt First—With A 'Friends' Costar!

We all know the story like this: Brad Pitt falls for Angelina Jolie on the set of Mr. & Mrs. Smith, Brad divorces Jennifer Aniston after five years to be with Angelina, which leaves Angelina to be portrayed as the sultry seductress, all while Jennifer Aniston looks like the poor girl next door who got her heart broken.

But there's a twist to the story that Star has exclusively learned about Jennifer Aniston's past. Paul LeBlanc (the father of Jen's Friends costar Matt LeBlanc—who played Joey on the hit show) spoke about his relationship with his estranged son.

"They would make out in the dressing rooms. He told me about it—it was when she was married to Brad Pitt," Paul LeBlanc exclusively told Star.

Their alleged affair occurred during their Friends days—more specifically three years into Jen's marriage to Brad, when Joey and Rachel got closer on the Season 9 finale.

During the season nine finale, which first aired in 2003, the plotline could have brought the stars closer in real life. But Jen has been outspoken about her feelings for Matt. "Talk about someone who can read me a mile away," she has said. "I know I seem obvious but... I'll be standing there and I see him giving me this look, and he says, 'Come over here, sit down, talk.' And he just gets you to lose it, if there's something to lose."

But how deep were Matt's feelings for Jen? Paul doesn't have the answer to any of those questions, but it's clear he definitely has opinions about the kind of women Matt is attracted to.

But is Jen's perception of Matt on point or not quite? Not according to his father, Paul. "Matt goes after dirt bags," Paul exclusively tells Star. A shocking thing for a father to say about his famous son, but Matt has been fairly open about his wild side over the years. In 2005, Matt admitted that he "got out of control" and went too far with a stripper during a rowdy night out at a club. There were also reports of widespread drug use that night.

Paul has no doubts his son's lifestyle will catch up with him. "He was as good looking as anyone in Hollywood, but he isn't going to age well," Paul believes. "He'll be a fat little guy. He's not someone who's going to keep himself toned down away from the cameras, because he pigs out. I'll see him with his gut hanging over his belt."

"On TV, he's a loving man, but in reality he's not," says Paul about his son, who he no longer stays in touch with at all.

Matt's and Jen's reps are categorically denying his dad's assertations—and Paul has little hope that he and Matt will ever speak again. "Unless he finds out I'm dying, I can't see that changing," he explains. "He's not the Joey everybody loves."