NEW YORK — After 24 years behind bars, mostly in state prison, Gregory Acevedo seemed like a survivor to his sister and mother — so they don’t understand what it was about being in the custody of the New York City Department of Correction that pushed him over the edge. The city says he died trying to escape. Acevedo, 48, climbed a fence Sept. 20 in the rooftop recreation yard of “the Barge” jailhouse moored off the Bronx in the East River formally known as the Vernon C. Bain Center. As an officer tried to stop him with pepper spray, Acevedo made his way through the razor wire atop the fence an…