The “Scream” actress penned a lengthy Instagram post Monday night after divulging the alleged sexual misconduct by Payne on Twitter.

“For years I had thought a man I had sexual relations with was a sexual experience I had,” she wrote. “I now know I was groomed. I auditioned for him at 15.”

The now-46-year-old said she came to a realization about Payne three weeks after sexual abuse allegations against Harvey Weinstein surfaced. McGowan has also accused Weinstein of raping her.

“I want you all to know that it’s not your fault if you were mentally massaged into thinking it’s okay. It is not,” she wrote. “I know this now. I would even go up to this director at events and ask him, with a smile, ‘remember when you had sex with me at 15?’ And I would laugh it off. That is deep societal programming.”

McGowan continued, “If you are out there trying to have sex with an underage minor, you are committing a crime, even if the minor doesn’t know it. I was attracted to him, so I thought it was on me, but that’s not correct. I was not an adult.”

The “Charmed” star said she didn’t want to name Payne on the Instagram post, calling the platform “my softer side.”

But she tweeted Monday, “Alexander Payne. You sat me down & played a soft-core porn movie you directed for Showtime under a different name. I still remember your apartment in Silverlake. You are very well-endowed. You left me on a street corner afterwards. I was 15.”

The alleged incident would’ve happened around 1988, when Payne, now 59, was about 27.

He’s won two Oscars for “The Descendants” and “Sideways.”

A rep for Payne didn’t immediately return a message.