This is so sad:  A Staten Island man was brutally stabbed for defending his brothers at his own engagement party yesterday. His fianceé tried to administer mouth to mouth to save his life but tragically, the man died at Staten Island University Hospital South. Get the full story after the jump…

Wendy L.

A Staten Island man was knifed to death at his engagement party early yesterday when two of his brothers went outside to urinate against the wall of a restaurant — sparking the deadly melee.

Antonio Lacertosa, 27, was stabbed in the torso with a butcher knife.

“This guy stabbed me! Call an ambulance!” he said.

His fiancée desperately administered mouth-to-mouth resuscitation in a valiant attempt to save the life of her love as he lay bleeding profusely outside Espana Restaurant, a source said.

But Bridgette Schneider, 24, couldn’t revive her would-be husband — and his friends couldn’t stanch his wound with a pile of restaurant linens they held to his ribs.

“They kept soaking through over and over,” said a witness.

Lacertosa, who had seven siblings, died at Staten Island University Hospital South.

“They were truly in love, and were eager to embark on their journey together,” Schneider’s sister, Rebecca, told The Post. “They loved each other to no end.”

Lacertosa’s sister, Jeanine Caruvana, said he proposed at the Rockefeller Center Christmas Tree lighting last fall.

“As soon as the lights went on, he gave her the ring,” Caruvana said, fighting back tears.

Schneider, Lacertosa, his brothers and their friends hit up the Annadale eatery about midnight for drinks after a more formal gathering.

As the party rolled on, restaurant managers ousted a pair of Lacertosa’s brothers in a dispute, said sources.

They retaliated by wizzing on the eatery’s exterior just before 2 a.m., police and sources said.

The restaurant manager and an associate spotted the peeing pair. “This is my place. What’s going on?” the manager yelled, according to a witness.

That’s when all hell broke loose.

A fight ensued, and the rest of the group spilled outside to help.

By then, the manager’s associate had allegedly pulled knives from the kitchen, sources said. “He’s got knives!” someone yelled out.

But Antonio apparently didn’t hear the warning, a witness said.

He ran into the fracas to help his brothers.

Moments later, the burly bricklayer was seen stumbling out to the front of the eatery, clutching his side. He seemed to finger the manager’s associate as his attacker before collapsing on the sidewalk.

The alleged stabber fled and was still at large last night.

The manager, who was not believed to have wielded the knife, turned himself in to police for questioning, sources said. It was unclear if he would be charged. He was identified as Ridi Zeneli according to a published report.

Lacertosa and Schneider had joined family and friends to mark their joyous engagement Friday with a party at Ariana’s, a Charleston catering hall.

The pair planned to wed after eight years of dating. They were planning a destination wedding and had been house hunting.

“Last night, him and my sister glowed,” said Rebecca Schneider.

She said her sister was sleeping in Antonio’s bed last night to still be close to him.

“A few hours ago we were celebrating the happiest time of her life. She was overjoyed. Now, she’s overwrought, inconsolable — there is no talking to her now,” a source said.

The victim had been helping his mother pay the mortgage since his father died in 2009.

“He was the breadwinner for my mother,” said Caruvana.

Joseph Lacertosa, 31, wept, calling his younger brother “a big teddy bear.”

“He’s a great guy, lighthearted,” said Joseph, a Marine. “I sent him a text at 1:57 a.m. and I just said: ‘Thanks, we had a great time,’ ” Joseph said. “I never got a text back. Then a friend called and said: ‘[Antonio]’s been stabbed.’ ”

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