Timothy Harrison's previous charges, including rape, after minor in 2013 have been dismissed in the plea, the DA's Office says.
The woman wrote an 8-page letter to a local board of education about the alleged abuse, which she said led her to consider suicide.
"They wanted to silence more victims," said Margaret Rohl, claiming that the BOE used intimidation tactics to belittle speakers on Monday.
The high school teacher who was escorted out of class last week after facing "disturbing allegations" will no longer be employed.
Attorney General Letitia James announced an investigation Tuesday morning, over "allegations of widespread sexual abuse and misconduct."
"For every one that comes forward, we have to imagine that there are more that don't feel comfortable — or who may never come forward."
The district, which was under scrutiny after accusations of sexual abuse against some staff, passed the measure with support of alumni.
Babylon residents will be encouraged to discuss matters of school district concern, organizer say.
"Trauma survivors need time to process their experiences, which are especially confusing for young people."