HefnerHarris230.jpgHugh Hefner's ex, Crystal Harris, went on Howard Stern's radio show Tuesday and revealed every detail of her sex life with Playboy magnate Hefner ... even if it meant sacrificing his dignity.

In the video (below), Harris, 25, tells Stern that she and Hefner, 85, only slept together once and that she stopped the intercourse soon after it began.

But Hefner, who we must say has taken the high road since being dumped by Harris only days before their June wedding, is refuting her claims.

"Crystal lied about our relationship on Howard Stern but I don't know why," Hef Tweeted Tuesday night. "Maybe a new boyfriend?"

Harris is reportedly dating Dr. Phil McGraw's son, Jordan. That Tweet has since been removed, but Hef Tweeted after:

    "I feel sorry for Crystal. She seems lost. ... Crystal convinced me that she adored me. That was the first lie. ... I'm happy to be in a better place with new girlfriends Anna Sophia Berglund & Shera Bechard."

Indeed, Hef has moved on. See what he and his new girlfriends did Tuesday night after the jump ...