Thorson speaks to The ENQUIRER as the couple's five-year relationship was recently the focus of HBO's critically-acclaimed Behind the Candelabra, launching the lavish piano player back into the public consciousness.
"There were sex parties left and right back then -- in the 70s and 80s, it was all about sex, drugs and rock n' roll," Thorson said, noting that while there were "piles" of cocaine available to partygoers, the maestro of the piano didn't take to the party powder du jour.
"He was very against that," Thorson told The ENQUIRER. "The only thing that Liberace liked was amyl nitrate, and marijuana, and his vodka tonic with a twist of lime."
Thorson named a laundry list of celebs -- Siegfried & Roy, Wayne Newton, Loretta Lynn, Larry Gatlin, Suzane Somers, Lena Horne and Engelbert Humperdinck -- who attended the parties, though he did not specify how they behaved.
Another famous face at the bashes, according to Thorson, was Rock Hudson, who like Liberace, was one of the first high-profile celebrities to fall to the AIDS virus during its' outbreak in the 80s.
Thorson said he's HIV negative, likely because of his "very cautious" attitude at the time.
"And I think its' the reason I'm alive today," he said.
He said that while he doesn't directly blame Liberace for the lifelong issues he's fought through, "There's a sense from quite a bit of my problems, with the plastic surgeries with the drug addiction … we did stupid things."
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Beginning when he was still a teen, Thorson (played by Matt Damon in the movie) dated Liberace for six years, from 1976 until 1982. Liberace, was born Wladziu Valentino Liberace, died of pneumonia caused by AIDS at 67 on February 4, 1987 in Palm Springs, Calif.
For more, stay tuned for part three of the Enquirer's exclusive video interview, right here on RadarOnline.com — or pick up a copy of the magazine, on newsstands now.