Disgraced Rep. George Santos was shamed into silence Friday outside a brief court appearance — berated by a group of angry protesters, including a man who accused him of killing his dog.

Amid repeated group chants of “Resign!” Richard Osthoff could be heard outside federal court in Central Islip, LI, yelling: “You killed my dog!,” and “Dog killer!,” according to a video clip and Osthoff’s account.

“He kicked me while I was at the lowest point in my life,” Osthoff told The Post over the phone as he rode back to his Freehold, NJ, home, three hours away from Long Island’s Suffolk County.

Moments earlier, the usually gabby Santos (R-NY), 34, entered federal court in Central Islip around noon for a hearing in a wide-ranging criminal fraud case against him.

The courtroom grew silent when the lying Long Island Republican walked in, clad in an ill-fitting gray suit jacket, a white shirt, tie and khakis.

Lawyers on both sides updated the court on the discovery process in the multiple-felony fraud, money-laundering, theft of public funds, and false statement counts against the freshman congressional fabulist.

Prosecutors had submitted 80,000 pages of documents, they said, and Santos defense lawyer Joe Murray asked the court to reschedule a Sept. 14 court date so the lawmaker can be on the floor of the House.

“That’s the first week when session begins,” Murray told the court.

The parties agreed on a Sept. 7 appearance.

Santos’ $500,000 bond — secured by his father and aunt — remained unchanged.

Osthoff told The Post that in 2016, Santos set up a GoFundMe site for his beloved service dog Sapphire, raising $3,000 to remove her life-threatening tumor.

But Santos – using his alias Anthony Devolder – then stole every penny donors had pledged, Osthoff alleged. Sapphire died soon after.

“My family, friends co-workers, stuff like that…  they all donated to this GoFundMe, and… I couldn’t go around after he stole the money and ask them for more donations,” Osthoff explained.

“She was dead at that point. He pretty much-dropped rope on the guillotine… I was homeless at the time, I couldn’t afford pretty much even to put beans in the pot,” said the 47-year-old veteran, who now has a home and three dogs.

The heckling outside of court on Friday was the second time Osthoff had confronted Santos since the incident, after learning his identity from news coverage of the alleged swindles.

Three weeks ago, Osthoff said he reached him by phone and repeated the accusations.

“He said, ‘I’m not having this conversation,’ and he hung up.”

“I would not have even been at this appearance today if he had just answered the phone and been copesetic and nice to me,” Osthoff said, explaining he just wanted “an apology.”

“So now I’m going to be at all of the appearances he ever has around here and I’m gonna, I’m gonna scream and yell and make some noise.”

When asked what he’d tell Santos now, Osthoff pulled no punches.

“You know me, George. You do know me. Stop lying. I’m not one to be gaslit… I’m an American veteran and I’m not a dumbass.

“You know what you did. Shame on you. Own up to it and be a man.”

The 34-year-old Santos, who admitted fabricating his professional career and defining details of his personal life before flipping New York’s 3rd Congressional District seat last November, is accused of embezzling $50,000 in campaign money, lying to Congress about his finances, misrepresenting himself to donors and stealing COVID unemployment benefits.

Santos’ antics have caused many mainstream Republicans to distance themselves from him, including House Speaker Kevin McCarthy (R-Calif.), who said last week Santos “shouldn’t run for re-election,” while resisting calling on him to resign.

The lawmaker, wearing sunglasses outside, was also tight-lipped leaving the courthouse, pausing only to take a small American flag from a supporter, and ignoring Osthoff and the other protestors.

Santos has pleaded not guilty to the 13-count indictment.