Sean “Diddy” Combs demanded Cassie Ventura pay him $20,000 — and threatened to release explicit “freak-off” videos of her — in a jealous rage over her relationship with Kid Cudi, her mother testified Tuesday.

The revelation came out as the R&B singer’s mom, Regina Ventura, took the stand at Combs’ Manhattan federal trial — and detailed how she and her husband took out a home equity loan to pay the music mogul’s outrageous ultimatum.

The multi-millionaire perversely demanded the cash in 2011 to “recoup” money he spent on Cassie Ventura, his on-and-off girlfriend, because he was angry about finding out she was dating the rapper, whose real name is Scott Mescudi.

“I was scared for my daughter’s safety,” Regina Ventura told the jury.

Mescudi is set to testify against Combs, possibly as soon as Wednesday or Thursday, prosecutors revealed.

Cassie Ventura’s frightened mother’s testimony dovetailed with her own harrowing account of an abusive decade-long relationship with the “All About the Benjamins” singer, during which time she contended he forced her to participate in degrading “freak-off” sex parties.

Combs had filmed many “freak-offs” and used the sex tapes as sick leverage, Cassie Ventura testified — an account her mother backed up.

Ventura sent her mom and Combs’ assistant, Capricorn Clark, an email on Dec. 23, 2011, that the jealous mogul was threatening to release “2 explicit sex tapes of me” and “he will be having someone hurt me and Scott Mescudi physically,” according to an email shown in court by prosecutors.

Regina Ventura testified she “was physically sick” after reading the emails.

“The sex tapes threw me,” she said. “I did not know the other person but I knew he was going to try to hurt my daughter.”

The mom transferred the money to a Bad Boy Records account, but the sum ended up getting returned in four or five days, she told jurors.

Shocking photos depicting Cassie Ventura’s bruised body after Combs alleged abuse also featured in her mother’s testimony.

Regina Ventura testified she took several of those snaps in 2011 — and that her daughter told her she was “beaten by Sean Combs.”

“I wanted to make sure we memorialized it,” the mother said.

Combs’ defense attorney Marc Agnifilo opted to not question Regina Ventura on cross-examination.

She walked past Combs, who sat with a clothing tag sticking out of his navy pants, without batting an eye.

Combs, 55, has pleaded not guilty to sex-trafficking and racketeering conspiracy charges. He could be sent to prison for life, if convicted.