A heartless NYPD cop and his wicked fiancée starved and tortured his autistic 8-year-old son, even mocking the child as he collapsed from the hypothermia that would claim his young life, officials said Friday as the Long Island couple was charged in the boy’s murder.

Michael Valva, 40, a 15-year officer assigned to the transit bureau, and fiancée Angela Pollina, 42, tried to make it look like they were as idyllic as the Brady Bunch, living with Valva’s three sons and Pollina’s three girls — each from previous relationships — at the couple’s home in Center Moriches, but their sitcom veneer hid a sinister secret, a former nanny said.

“It’s sad. They wanted to give the impression they were the ‘Brady Bunch’ family when it was more like a home crashing,” Amanda Wildman, who babysat the family from 2017 to 2018, told The Post.

“There was always screaming. The boys were constantly being yelled at. There never was a day where somebody wasn’t screaming and the boys would just sit there quietly and take it.”

On Friday, Valva and Pollina were arrested and charged with second-degree murder for the Jan. 17 death of Valva’s son Thomas, who died of hypothermia after being exiled to a “freezing” unfinished garage at the couple’s home on Bittersweet Lane the night before — when temperatures outside plummeted to a bone-chilling 19 degrees, Suffolk County Police Commissioner Geraldine Hart told reporters.

“We believe certainly that Thomas was kept in the garage overnight preceding his death,” the commissioner said.

Prosecutors revealed at Valva’s arraignment that he and Pollina even taunted Thomas for being cold on the morning he died — after keeping him in the freezing garage all night.

Thomas was “face-planting” on the floor because he was hypothermic, Assistant District Attorney Laura Newcombe said, citing audio recordings taken from an extensive home-security system in the house.

In the recording, a child can be heard asking why Thomas cannot walk.

“Because he’s hypothermic,” Pollina replied, according to Newcombe. “When you wash with cold water and it’s freezing out you become hypothermic.”

Later, Pollina put the same question to Valva.

“Do you know why he’s falling?” Pollina asked Valva about Thomas, Newcombe said, citing recordings.

“Because he’s cold. Boo f–king hoo,” Valva callously responded, according to the prosecutor.

When Pollina apparently walked into the garage and asked Valva what he was doing, Valva said: “I’m f–king suffocating him that’s what I’m doing,” prompting Pollina to say, “Take your hands off his mouth. There are people everywhere,” according to Newcombe.

Authorities responded to the home at 9:40 a.m. that day, after Valva reported that his son fell in the driveway while waiting for the school bus an hour earlier.

Valva, who was immediately suspended without pay and stripped of his guns, told cops his son lost consciousness after the fall, according to Hart.

“When officers arrived, Michael Valva was performing CPR on his son in the basement,” she said.

Medics rushed the boy to Long Island Community Hospital and when he arrived there, his body temperature was just 76 degrees, according to Hart. He was pronounced dead at the hospital.

Valva allegedly put the boy’s body in a warm bath in order to raise his body temperature before calling cops, a police source told The Post.

An investigation “revealed inconsistencies in timing and nature of the child’s injuries as reported by the father,” said Hart, who noted that police determined that the boy was never in the driveway that morning.

Thomas suffered head and facial injuries “that were not consistent with” Valva’s account, and the medical examiner ruled the boy’s death a homicide “with a major contributing factor of hypothermia,” Hart said.

The Suffolk County source told The Post that Valva got angry with Thomas and beat the boy the day before his death.

As punishment, Thomas was ordered to stay in the garage, the source said.

Hart noted that the investigators reviewed audio and video surveillance of Valva and Pollina from outside and inside the home and the recordings “show the pair was closely monitoring the activities and conversations of their six children.”

Prosecutors said that nearly every room in the home was equipped with surveillance cameras that were labeled according to the child’s name and room.

The camera located in the garage was eerily labeled “kids room.”

Investigators believe Thomas, as well as his 10-year-old brother, Anthony, were subjected to punishment, including “food deprivation and exposure to extremely frigid temperatures,” Hart said, adding, “We are still investigating the extent of the abuse and if it extended to all of the children.”

Home surveillance footage captured Thomas and Anthony sleeping on the concrete floor of the garage and “shivering” two nights before Thomas died, prosecutors said.

“They are on cold concrete. There are no pillows, no blankets, no mattress,” Newcombe said.

Hart noted that authorities did a welfare check at the residence in May 2019, but the family was not home at the time.

“This case has hit our department hard, even our most seasoned detectives,” the commissioner said.

Thomas and his 6- and 10-year-old brothers lived at the home along with Pollina’s three daughters — 11-year-old twins and an 8-year-old girl, authorities said.

Child Protective Services removed all five surviving children from the home after the parents were arrested, Hart said.

Thomas’ brothers were with their biological mother, Justyna Zubko-Valva, 36, on Friday.

Zubko-Valva, who says she “unlawfully” lost custody of her three children in 2017, claimed that her kids were abused at the hands of their dad for years and ignored by those with the authority to help.

“There are so many people responsible for this tragedy,” Zubko-Valva, who is divorced from Valva, told The Post.

“The institutions that are supposed to protect the children protect the abusers,” said Zubko-Valva who claimed that she reported to law enforcement and child protective agencies and judges about the alleged abuse of her three young boys.

Thomas had autism and his 10-year-old brother, Anthony, has a learning disability, the mom said.

Zubko-Valva said she warned judges over the years during various court proceedings that, “My children are gonna die from the sadistic and abusive care of Michael Valva and Angela Pollina.”

The helpless mother even detailed the alleged abuse on a Twitter account she created in January 2018 under the name “StandAgainstChildAbuse.”

In one tweet, she posted what appears to be a 2018 report from the East Moriches School District detailing how Thomas and Anthony, were being neglected by Valva and Pollina.

“Biggest concern is that Mr. Valva and his fiancée Angela do not understand the depth of Anthony and Thomas’s disabilities,” reads the letter, written by a school psychologist.

The letter went on to say that “both Anthony and Thomas come into school hungry and frequently say they did not eat breakfast because they did not ask for breakfast or got in trouble.”

Another apparent school letter posted to the account states: “Anthony and Thomas have stated that they were not allowed to eat breakfast because they did not use their manners, say ‘good morning’ to Angela or were doing nothing. They have come in crying because of this.”

The school district refused to comment on the documents.

Valva and Pollina pleaded not guilty at their arraignments and were held without bail.