A “pretentious” Manhattan socialite hosted a swanky, “black tie optional” bash in January — where he sipped champagne with his fabulous friends and boasted of an upcoming years-long vacation to Europe he was about take.

Tabber Benedict bellied up to the bar at Chelsea’s Bungalow 8 — with a woman on his arm — and bent his friends’ ears about the planned jaunt and all the places he was going to visit.

But the finance lawyer was hiding the real, sinister reason he was saying his farewells.

He was going to prison for nearly killing a man.

About two years ago, the West Village denizen slammed his SUV into a Long Island dad after a night of hard partying in the Hamptons — and left his victim for dead, records show.

The Jan. 24 soiree was just four days before he was sentenced to as many as 10 years in the clink.

“He lied to everybody about going to Europe,” one of his friends said.

But throughout the party — which began at 11 pm — Benedict, 35, played it cool, some of the 150 attendees said.

The socialite, who often appears impeccably dressed at charity events, was recently featured in a New York Observer story about “Gatsbabies” — described as “preening prepsters” who “lure ladies, lucre and limelight” as a lifestyle.

“People look at me and they’re like, ‘That spoiled prick,’” Benedict, who says his financial law firm handled $25 billion in transactions, told the paper.

The scenesters scored the space at Bungalow 8 for free, because they know a woman who runs the door at the club, attendees said.

It wasn’t until later that one friend “heard that [Benedict] was making something up” and that only a few people “did know the truth.”

The truth was that Benedict was partying at a friend’s house in the Hamptons on July 4, 2011 when his girlfriend demanded he come see her in Manhattan, his lawyer said.

Benedict took to the road at 8 a.m. with a .28 blood-alcohol reading — more than three times over the legal limit, law enforcement sources said.

While driving along Montauk Highway in East Quogue, Benedict drunkenly plowed his GMC Acadia in to Steven Dorn, 45, a high school teacher and father of three daughters who was cycling, court records state.

The “Gatsbaby” then fled the scene as the dad lay severely injured along the highway, court records show.

Two other drivers on the road — identified as Bernic Daly and his uncle John Daly, who were in separate cars — sped up to Benedict and blocked his SUV so he would stop, law enforcement sources said.

The jet-setter pleaded guilty to 10 total charges — including aggravated vehicular assault, DWI, and leaving the scene of an accident — and was disbarred from practicing law.

Dorn, a a father of three who is also a local lifeguard in the summer, endured a grueling recovery, and only recently returned to work in the William Floyd School District as a physical education teacher.

Benedict finally faced his victim at this emotionally-charged Jan. 28 sentencing.

“I have a nine-inch laceration from my back that goes to my stomach, which we have as a lifelong reminder that I was almost killed that day,” Dorn told the court, records show.

“He left me on the side of the road to die and he then fled to save himself.”

Dorn also skewered Benedict for never apologizing.

“This tragic experience has been very difficult because of the fact that Mr. Benedict has shown no remorse,” he told the court.

“He’s never apologized or reached out to me and my family.

“To this day I cannot do things with my children without constant pain in my back or hip.”

And Dorn’s wife, Deanna, told the judge said Benedict “changed our lives.”

“Your honor, ironically, it was Independence Day of 2011 that Steve and I lost our independence.”

But Benedict’s mother, Sharyn Kerrigan, rushed to his defense, writing to the judge about his humble upbringing in East Greenbush, a town right outside Albany.

“He’s destroyed Mr. Dorn’s life and destroyed his own in the same breath,” she wrote.

“Unfortunately we can’t go back in time to change it.

“Tabber is not a wicked man, nor does he come from money, but has worked hard all of his life and contributes much of his time and money for free to helping others,” she wrote in a letter to the court.

Benedict’s social cache stems from high-profile parties he organizes for various charities, such as the Avon Walk for Breast Cancer.

His mother also noted that Benedict had to overcome limited mobility on the left side of his body due to a congenital nerve defect.

“I am begging the Court to show mercy for everyone today and to find forgiveness in this courtroom,” she concluded, records show.

Benedict also finally apologized to his victim during his sentencing.

“I am so sorry for what I did to your family, what I did to Mr. Dorn, his wife and your children and how I impacted you,” he said in court, records show.

“Not a day goes by that I don’t feel awful.”

But Suffolk County Judge James Hudson wasn’t buying it — and slapped Benedict with a sentence of three to 10-year sentence for aggravated vehicular assault at an upstate prison.

“You almost took everything that a man values and loves from him,” the judge said, records show.

“And that is why you must go to prison for it.”

And in the end, even Benedict’s friends weren’t moved.

“I feel terrible for Tabber because I know there’s no table service where he’s headed,” sniffed fellow socialite Justin Ross Lee.

“He’s the most pretentious person I’ve ever met.”