An NYPD cop who said he joined a violent robbery crew targeting drug dealers to pay his mortgage was slammed yesterday with 20 years in prison by an outraged judge.

Officer Jorge Arbaje-Diaz emigrated from the Dominican Republic at age 19, earned a college degree and joined the NYPD in 2005 - then disgraced his badge because he couldn't make the monthly payments on a new house.

That lame excuse didn't sit well with Brooklyn Federal Judge Nicholas Garaufis.

"The idea that he was motivated by a variable-rate mortgage puts us in the world of the absurd," Garaufis said in court.

"Mr. Arbaje-Diaz, you are the poster boy for a sentence that will deter others from doing the acts you engaged in," the judge roared.

The former transit cop, who was fired from the force after pleading guilty in May 2010, apologized to his family, but never mentioned the tarnish he put on the badge.

Defense lawyer Priya Chaudhry tried to win sympathy for his client in sentencing papers that, in part, blamed the pay that city cops take home.

"Jorge was shocked to see that this house his family loved quickly became something he could not afford on his NYPD salary," she wrote. "There seemed no way out until one day the Devil appeared on his shoulder in a barbershop."

The cop's pals introduced him to members of a gang who posed as cops to rob and torture their dealer victims into handing over drug money.

Prosecutor Jeremy Shockett noted that Arbaje-Diaz participated in half a dozen robberies, including one while in uniform and on duty, and another in which a child was held at gunpoint. "Some would say he had the American Dream ... and he threw that away in extraordinary fashion," Shockett said.

Arbaje-Diaz, 33, flashed the peace sign and blew kisses to his wife and children, who were sitting in the courtroom.

He told the judge it was difficult even for him to figure out how "a person educated in morals" could make such bad choices.

"I got carried away by the reckless character of youth," Arbaje-Diaz said.