EXCLUSIVE: 'Sopranos' Star Vincent Pastore's 'Biggest Regret' Revealed After Death

Beloved Sopranos star Vincent Pastore was mourned by castmates and fans after his sudden death Aug. 1 at 80 years old – but he took a dark secret shame to the grave with him, RadarOnline.com can reveal.

Despite playing mob heavies for decades in television and the movies, the hulking former nightclub bouncer was known for his jovial good nature. But there was one shameful episode in his past that he wished never happened, according to sources close to the star.

On April 2, 2005, Pastore – who played Salvatore "Big P----" Bonpensiero, Tony Soprano's turncoat right-hand man in the hit HBO series – had his own humiliating run-in with the law, leading him to plead guilty to an attempted assault on his then girlfriend, Lisa Regina, on the streets of New York's Little Italy.

Prosecutors said the big-screen enforcer punched the woman in the back of the head, grabbed her hair and forced her head down on a car's gear shift. During his appearance before Manhattan Criminal Court Judge Ellen Coin, Pastore was asked if he attempted to strike Regina. "Yes, I did," he replied.

Regina was also granted a four-year order of protection against the Goodfellas actor, with the judge warning him that breaking it would result in his landing behind bars for four years.

As part of the then 59-year-old's plea deal, he agreed to complete 70 hours of community service, attend six months of weekly anger management therapy, and pay a $190 fine.

The following year, the battered woman, now 65, sued the actor, reportedly winning a $5.5million settlement in 2009 for the incident, with lawyers for both sides saying the terms were "confidential."

Court testimony revealed Pastore admitted he began fighting with Regina when she tried to call a former boyfriend and wept when he concluded that she didn't love him. He also said that he yanked her out of his car by her hair and tossed her luggage onto the street when she yelled: "Big P----'s beating me up!"