A dazzling blond former Hunter College student was fatally stabbed and nearly decapitated Sunday after battling with her live-in boyfriend, cops said.

The yelling between Sarah Coit, 23, and Raul Barrera, 33, inside their third-floor lower East Side apartment grew so loud that it woke neighbors around 2:15 a.m., witnesses said.

Cops would later find Coit on the living room floor of the Clinton St. flat, *la*hd spilling from her wounds.

"Her whole neck was cut all the way," said Briana Andalore, 20, who lives downstairs and saw the victim being hauled away on a stretcher. "Her head was almost cut off."

Coit, who worked sales at Lacoste, sources said, and last enrolled at Hunter a year ago, according to the school, died at Beth Israel Medical Center about an hour later.

The roars of the couple's fighting - which sources said was about the pair splitting up - echoed throughout their apartment walls for about 20 minutes, neighbors said.

Jason Figueroa, 15, who lives just above the couple's apartment, said he heard arguing and then what sounded like Coit being attacked.

He called cops.

"She was like, 'Stop! Get off of me!'" said the shaken teen.

"She was yelling and then she just got quiet," he said, "That's when I called 911."

Several others tried to answer Coit's *la*hdcurdling cries, but to no avail.

"She was screaming," said Joost Bohner, 33, a tourist from Holland staying next-door.

"People tried to help her," he said. "Then it was quiet."

Police sources said cops found Coit with several stab wounds to her body - and her neck sliced open.

Barrera, who was arrested last year for allegedly assaulting a man, turned himself in at the 9th Precinct stationhouse in the East Village soon after the grisly murder when a relative urged him to go to the police, sources said.

He was then taken to the 7th Precinct stationhouse, where he was charged with second-degree murder.

Barrera, wearing a light-colored jumpsuit, showed no emotion and said nothing to reporters as he was walked out of the stationhouse. He was still awaiting arraignment last night.

Neighbors said they had heard the couple argue before, but never so loud. Police said they had not been called to the address before yesterday.

A family friend in Coit's ritzy hometown of Riverside, Conn., near Greenwich, said she was heartbroken for the family.

"[Coit] was their only daughter," said the woman, who did not want to give her name.

"She was a great young woman," she said. "They are wonderful people."

Records show Coit's father, Lynde Coit, is a prominent financial adviser. He and his wife, Anne Taylor, could not be reached for comment.

One of Coit's two brothers, Stephen, declined to speak when contacted by the Daily News.

According to Coit's LinkedIn profile, she was studying for a career in marketing and advertising.

Barrera worked in public relations for companies such as Propaganda NY and Coleman Entertainment Group.

Derek Guadalupe, the superintendent of Coit's former home on the upper East Side, said the young beauty was always busy with her schoolwork.

"She was a nice kid," he said. "It's a shame what happened. It's sad. She had a future ahead of her."