An Upper West Side special needs teacher says she was beaten up by a mother she reported to authorities for suspected child neglect — and now the educator is suing the city for failing to protect her.

Former PS 84 teacher Jessica Golian, 29, was reluctant to report Jennifer DeJesus to authorities in June 2015 when her two kids started arriving late to school reeking of marijuana, her Manhattan federal court lawsuit alleges.

But a worker with the state Central Register of Child Abuse and Maltreatment promised the teacher — who lives in the same neighborhood as DeJesus — that her name would remain confidential, even though the report would be public.

Golian told the worker she was also worried about making the report because she knew DeJesus had “violent proclivities,” the suit alleges.

“I said, ‘But I’m really scared.’ She said, ‘You have to leave your name, I assure you, your name will not be brought up to her,’” recalled Golian, who is required by law to report suspected child neglect.

“I’m a mandated reporter so I had to call. It was part of my job,” she told The Post.

Several months later, after the city Administration for Children’s Services pursued its investigation into the neglect allegations, DeJesus attacked Golian as she left work, the suit says.

The mom grabbed Golian and slammed her to the ground, whispering, “I know what you did,” according to a criminal complaint filed against DeJesus by the Manhattan DA’s Office.

As Golian tried dialing 911, DeJesus grabbed her phone and stomped on it, court papers say.

The attack left Golian with “serious neck and back injuries,” said her lawyer Gerald Cohen. He declined to go into specifics.

DeJesus pleaded guilty to misdemeanor assault in exchange for three years’ probation. There is an order of protection against her barring her from contacting the teacher.

Still, Golian said she’s fearful the mom could attack again and has gotten a “safety transfer” to teach at a new, undisclosed school.

“Basically, she got away with the whole thing,” said Golian. “What does that show her, that you can just beat up a teacher because it’s no big deal? I’m still terrified of her.”

Golian is suing the city, ACS, the worker who took her complaint and DeJesus personally, saying her name should have never been released.

“I hear from other teachers all the time that parents find out and threaten them,” said Golian. “I would really love for there to actually be a consequence when ACS breaches confidentiality. I just feel like by doing my job, I’m protecting [my students] but there’s literally nobody protecting me.”

ACS deferred questions to the city Law Department.

“Protecting the identity of mandated reporters is crucial,” a spokesman said. “The city will review the complaint and investigate the facts to determine what actually happened in this situation.”

Reached at her West 90th Street home, DeJesus denied neglecting her kids, now ages 8 and 10 — and also denied laying a finger on Golian.

“I just politely told her that I know what she had did and she started running from me,” said DeJesus, 28. “She came up to me to give me a hug and I told her that I know what she had done and that’s it. Her eyes started to bulge and she started running back toward the school.”