Robert De Niro’s ex-assistant said the actor’s girlfriend Tiffany Chen was “f–ing nuts” and a “sociopath” during phone calls with colleagues, which were played for jurors as she was cross-examined in Manhattan court on Monday.

“She has Munchausen’s,” Graham Chase Robinson said during one of the calls, referring to the syndrome commonly associated with sufferers who pathologically feign illness or suffering to draw attention to themselves.

Robinson secretly recorded the phone calls in March 2019 when Chen, 45, was reportedly having a meltdown about mold in De Niro’s Upper East Side townhouse as the building was being renovated.

“She’s f—ing nuts,” the ex-assistant said of Chen in another call, before comparing her to De Niro’s ex-wife, Grace Hightower.

“Grace I understood. She was the Devil that I knew. She did it by bullying and staring at you …Tiffany is a sociopath. She’s going a completely different way.”

The calls were played in the ongoing legal battle between De Niro, 80, and Robinson, 41, who have both accused each other of nasty behavior during their 11 years working together between 2008 and 2019.

Robinson’s relationship with Chen has become a touchpoint during the trial, with the two lobbing back and forth accusations of being territorial over De Niro.

On Thursday, Chen testified that Robinson had delusions of an “imagined intimacy” with her boss and that she was angling to become his wife.

Tensions grew so high that Chen said she even issued an ultimatum to De Niro in March 2019 telling him that he would need to pick between her and his assistant. During her testimony, Chen frequently used words like “psychotic,” “crazy,” and “nuts” to describe Robinson.

On Monday, Robinson admitted to using many of the same words — “psychotic,” “sociopathic,” and “drunk with power” — to describe Chen.

During one phone call played in court, Robinson appeared to plot taking time off work to try to make De Niro see what a menace Chen was.

“I want Tiffany to kick up the drama so it’s like, ‘Did Chase have it? Did Chase have it? Did I break her?'” she said on the call.

De Niro’s production company, Canal Productions, sued Robinson after she resigned in 2019, accusing her of stealing millions of frequent flier miles from the actor.

She countersued a few months later and accused him of subjecting her to sexual harassment and being a hellish boss.

Robinson’s attorney told the court on Monday that she’d received a nasty text hours before the session, which he speculated had been sent from one of De Niro’s children, according to the Daily Mail.

“You disgusting little beast. You have nothing better to do with your pathetic life than destroy an 80-year-old man’s life,” the lawyer read aloud from the text message. “Hopefully you and your family will suffer as you have made others suffer.”

The text was sent from an unknown number, but Robinson’s attorney said her iPhone’s suggested sender name was the same as one of De Niro’s children.