A porn star claims her world-famous violinist ex-boyfriend is a pervert who forced her to drink his urine and tried to hire a sex slave, according to a new $12 million lawsuit.

David Garrett — a Juilliard-trained violinist known as “the David Beckham of classical music” — asked X-rated actress Ashley Youdan to marry him just days after he paid her for sex in August 2014, her Manhattan civil suit says.

The bad-boy bow pusher — whose long blond hair and scruffy beard make him look more Kurt Cobain than Itzhak Perlman — soon moved Youdan into his Manhattan apartment and introduced her to his family and friends as his fiancée, the suit says.

Youdan, 28, claims in court papers that she began jetting to Malta, Mexico and Spain with the frisky fiddler, who earned the title of world’s fastest violinist when he played “Flight of the Bumblebee” in 66 seconds in 2008.

Garrett, 35, asked Youdan — whose porn name is Kendall Karson — to give up her adult-film career, and she did, her suit says.

Then, on Christmas Day 2014, Garrett’s “behavior began to take a dark turn for the worse,” the suit says.

“After seeing an advertisement for a ‘sex slave’ on the website Craigslist, [Garrett] responded to the advertisement hoping to perform ‘BDSM’ acts on the ‘sex slave’ and place the ‘sex slave’ in a cage while [he] and [Youdan] attended a nightclub,” the suit says.

Although Garrett corresponded with the sex slave and waited for her outside his apartment, she never arrived, the suit says.

Then, on Jan. 7, 2015, Garrett forced Youdan to drink his urine, according to court papers. Garrett also forced her into rough sex that left her with a fractured rib, the suit claims.

“Even I think this is awful, and I’m an expert in awful,” said Youdan’s lawyer Eddie Hayes, a former Bronx homicide prosecutor.

The pair broke up in February, and Youdan is suing him, alleging physical and mental abuse.

“The complaint is supported by voice recordings, photographs and medical records,” said Elisabeth Conroy, another lawyer for Youdan.

Garrett’s lawyer, Brian Maas, called the allegations “outrageous and baseless,’’ adding, “We have not received any lawsuit from Youdan, though her willingness to publicly level these meritless charges fits with a pattern of behavior of someone who has made numerous threats to David.”