“THREE WORDS. YEARS OF WAITING.” For the first time, the man accused in the Gilgo Beach k*llings was forced to sit face-to-face with victims’ families, turning an already emotional courtroom hearing into a moment many had been waiting years to witness.

Long Island serial killer Rex Heuermann chillingly told a disgusted judge “I am responsible” before he was sentenced to three life terms behind bars on Wednesday. Heuermann, who…