A Staten Island assistant principal convicted of stabbing his wife’s ex-lover cannot be slashed from his city job, The Post has learned.

Vincent Scotto, a well-liked administrator at PS 22 Graniteville, shocked the community in 2016 when he was arrested for attacking ex-con John Carosella, who allegedly dealt his wife cocaine and had an affair with her, records show.

Scotto hacked Carosella with a razor blade on a stick, cutting his arm and chest.

In a plea deal with the Staten Island District Attorney, Scotto’s original felony charge was downgraded last April to a misdemeanor after a year on probation. He was taken off the city payroll during that time.

The city Department of Education then tried to fire Scotto, saying it doesn’t run a “jobs program for people convicted of violent behavior.”

District 31 Superintendent Anthony Lodico said Scotto must be terminated “because of concern for the safety of students.”

A hearing officer, Haydee’ Rosario, found Scotto guilty of neglect of duty, criminal conduct and conduct unbecoming his position.

But Rosario ruled that Scotto, 46, deserved a second chance. She slapped him with the suspension already served, and ordered him reinstated last summer. His salary: $124,678.

The June 4, 2016 attack occurred when hostility between Scotto and Carosella escalated, and the two men met in the parking lot of a shopping center on Amboy Road.

In his DOE hearing, Scotto testified he feared for his toddler, who was with him, and claimed Carosella brandished a knife before he slashed him with the razor blade.

An NYPD detective testified that Carosella had a record of 17 arrests since 1985 for offenses including illegal drug and weapon possession and unlawful imprisonment.

The detective also confirmed that Scotto had filed police reports between 2013 and 2015 that Carosella was menacing and harassing him.

Scotto claimed Carosella once tossed a pumpkin through his car windshield, ripped off the mailbox at his home, and left voice messages at PS 22 calling his wife “a slut.”

His wife, Kerry, told cops Carosella was a “drug dealer” who gave her cocaine, and they had an affair four or five years earlier, Rosario’s report said.

However, Scotto’s PS 22 colleagues testified the stabbing incident had not ruptured their trust in him. Principal Melissa Donath praised Scotto as a dedicated “father figure” to students, and supportive of teachers. Several teachers vouched for Scotto’s character, one saying she “would be honored to have him back.”

DOE spokesman Douglas Cohen called Scotto’s act of violence “deeply disturbing.” He said Scotto was not returned to PS 22, but serves as a substitute assistant principal in Staten Island, currently at PS 31.

Scotto declined to comment through his lawyer, Anthony Varbero, who said, “He’s happy to be back” at work.

Carosella is now suing Scotto in Staten Island Supreme Court for injuries suffered in the stabbing. His lawyer did not return a call.