A Manhattan man haunted by the repeated sexual abuse he says he endured as a 13-year-old student at the elite Horace Mann School spoke publicly about the violations for the first time yesterday.

“The effects of that abuse on my life have been profound,” Ron Klepper, 48, said. “School was no longer a safe place to learn, but turned into a frightening place where a predator lurked.”

Klepper joined attorney Gloria Allred and five other victims at a press conference to call on the state Legislature to pass a bill to allow them to bring civil lawsuits against the Bronx prep school.

The victims, now in their 40s and 50s, want lawmakers to approve the Child Victims Act bill, sponsored by Assemblywoman Margaret Markey (D-Queens).

It would provide a one-year window in the statute of limitations that now prevents adults who were sexually abused as kids from filing claims after they turn 23.

The NYPD cut off its Horace Mann investigation because, under state law, the incidents happened too long ago to prosecute.

Another victim Jon Seiger, 51, described how eight faculty members used him as a “sex object and personal plaything.” He called for an investigation by the school.

“Instead of a safe, nurturing place that would educate me, Horace Mann ended up providing a perfect storm of childhood sexual abuse,” he said, claiming he was first raped and forced to give oral sex to headmaster Inky Clark at age 14.

All the abusers named by the victims yesterday are dead.

A group of alumni recently hired former sex-crimes prosecutor Leslie Crocker Snyder to lead an independent probe into the abuse. The Bronx DA is also investigating.

Allred said the school itself must investigate because “they’re the only ones that have the records.”

Another victim, Daniel Shapiro, 57, an attorney for New Jersey, demanded the school apologize.

“Talking today is very difficult for me,” he said in his first public statements. “More must be done to remove the shame and stigma of childhood sexual abuse.”

Shapiro was first molested at age 15, and he buried his secret for more than 35 years.

The private school is accused of turning a blind eye to the abuse, which targeted some 30 students from the 1970s through the 1990s.

Horace Mann has reached confidential settlements with about 20 victims. School reps didn’t immediately return calls for comment.