Amy Grossberg's life once seemed charmed.

Two years ago, she was an 18-year-old YMCA summer counselor, working with children, preparing to enter University of Delaware. She was a budding artist with a devoted boyfriend in Brian Peterson, a telegenic high school athlete set to attend college just three hours away."Friends may come and go, but those who truly love you will never leave you," Grossberg wrote under her photo in the Ramapo High School yearbook.

Friday, Grossberg marked her 20th birthday behind bars at the Delores J. Baylor Correctional Institution, sentenced Thursday to 2 1/2 years in jail for killing her newborn son, whose father threw his body into the trash.

"I'm extremely sorry for what happened to my baby. I blame nobody but myself," Grossberg said in the courtroom. "It's something I'll never be able to forget. That pain inside will be with me for the rest of my life."

With tears running down her cheeks, she told her parents she loved them as she was led away.

For his role in the baby's death, Peterson, 20, was sentenced to two years in prison - a lesser punishment because he cooperated with prosecutors and had tried to persuade Grossberg to seek medical help before she gave birth.

Peterson told Judge Henry duPont Ridgely: "Mistakes were made that cost my son's life and all I can say is I'm so sorry for what happened."

The two former lovers from Wyckoff, N.J., wouldn't even look at each other across the courtroom Thursday, a stark contrast to early court hearings when they would hold hands and whisper to one another.

Police said Grossberg gave birth in a motel in Newark on Nov. 12, 1996, after keeping her pregnancy secret from her family and friends.

Peterson put the newborn in a garbage bag and threw it in a trash container behind the motel. An autopsy revealed the infant died of massive head trauma and was alive at birth, not stillborn as both defendants had believed.

Prosecutor Peter Letang said Peterson told them he heard the bag smack against the back of the trash bin, possibly accounting for the skull fractures listed as a cause of death. The baby also died of exposure and lack of oxygen, he said.

"The call has got to go out to the Brian Petersons of this world to stand up before the baby is born," Letang said.