The Brooklyn teen who allegedly stabbed his abusive father to death in July has been so scarred by the ordeal he has spent the last month in a psychiatric ward, his lawyer told a judge Friday.

Hassan Razzaq, 19, is being treated at Weill Cornell’s Payne Whitney Clinic in Manhattan for the trauma of the killing and the years of violent physical and sexual abuse he endured at the hands of his father, said attorney Michael Cibella in Brooklyn Supreme Court.

Razzaq, who was sprung from Rikers Island on $1 million bond two months ago, “voluntarily” checked himself in, Cibella says.

“He’s in one of the best psychiatric hospitals in the city,” the lawyer said outside court. “They obviously see a need to continue treatment for the years of abuse he sustained.”

The college student is charged with plunging a knife into dad Mohammad’s throat after the man unexpectedly returned from Pakistan — and took out his rage over a failed business deal on Hassan and his 15-year-old sister, beating them in the hours before his death.