Rappaport filed for divorce from Sarah Mutch back in February. In a new civil lawsuit just filed, Rappaport says almost immediately after their lavish, $3 million wedding, Mutch began bitterly complaining about the terms of the prenup and demanded -- "violently at times" -- that he change the terms or "the marriage is over."

His lawsuit goes on to say ... when he refused to tear up the prenup, she went wild with his credit card, charging hundreds of thousands of dollars for various things. The suit claims Mutch threatened that if he didn't pay her bills, she would "release false information about [Rappaport] and his friends to the press and social media outlets."

He says after he filed for divorce, she went on a rampage, demanding millions of dollars or she would "go to the press and f*** s*** up" by disseminating false information about him and his celebrity friends.

Rappaport filed a police report in April, detailing some of the alleged threats. According to the report, obtained by TMZ, Rappaport says Mutch "threatened to fabricate a 'Me Too' sexual harassment report at the hands of his wealthy friends." He says she threatened to go to the media with the allegations if he didn't give her "millions and millions of dollars." He told cops she said, "If I don't get what I want, I'm going to drop a bomb and end your career in a week!"

He says one of her demands was that he give her partial ownership of a $60 million property he owns.

Rappaport says when he refused to put the property in her name or tear up the prenup during the marriage, she began berating him, calling him "selfish, cheap, greedy and disgusting."

The $3 million wedding in September 2017, was crazy ... Christina Aguilera performed. The guest list included Diddy, Ryan Seacrest, DJ Khaled and Larry King.