Administrators at The New School let a star psychology professor who sexually harassed multiple students and even participated in an orgy with lab students quietly resign, according to a lawsuit by one of his alleged victims.

The woman, a 23-year-old identified as Jane Doe in Manhattan Supreme Court papers, says she made it through undergraduate studies at the Greenwich Village university with a 3.7 grade-point average while battling cancer — but now claims in a suit against the school that she can’t focus on her studies because of trauma stemming from her encounters with professor Emanuele Castano.

The 43-year-old Italian native was the recipient of the prestigious National Education Association grant in 2016 when he started “grooming [Doe] for a sexual relationship,” the suit says.

Doe claims the divorced dad plied her with booze and pot after inviting her to dinner with him and his son at his home on March 3, 2017.

The student claims the professor “advanced himself on me, but didn’t stop to ask me whether I was OK with this,” after the boy had gone to sleep.

She continued sleeping with Castano, but felt that he exploited her as she was still recovering from lymphoma, the suit claims.

Their relationship deteriorated after Doe discovered Castano was sleeping with a post-doctoral student, according to court papers.

When she learned she was pregnant, allegedly with his child, Castano tried to bribe her to have an abortion by promising her a research opportunity in Italy, the suit claims. She eventually terminated the pregnancy so she could receive continued cancer treatment.

Last July, Doe complained to school administrators, saying in a statement, “I had sexual intercourse, unwillingly, with my boss/professor/advisor over 10 times.”

She says school officials took months to investigate, even though there’d been a previous sexual misconduct complaint about Castano in 2012 and a letter stating that a student had asked to be transferred after Castano had group sex with her classmates.

Instead of terminating Castano, he was allowed to quietly resign last fall and secured a position at Stanford University, which fired him after the student newspaper wrote about his New York past.

Castano, who according to the suit denied Doe’s claims to New School administrators, did not return a message from The Post seeking comment.

A university spokeswoman said, “It is our policy not to comment on pending litigation. The New School has no tolerance for sexual harassment and misconduct by any member of the university community, and we take our responsibility in these matters very seriously.”

Additional reporting by Gabrielle Fonrouge