Ex-NYPD cop Michael Valva and his former fiancée are blaming each other in the death of his 8-year-old son — and they want separate trials to prove it, their lawyers said Wednesday.

Valva’s lawyer John LoTurco called his client’s ex, Angela Pollina, a “wicked stepmother” in claiming she “is primarily responsible” for 8-year-old Thomas Valva’s death last year at their Long Island home.

“She was in charge of the children. She was the disciplinarian in the relationship,” LoTurco told reporters outside Suffolk County Supreme Court, where pre-trial hearings in the case have been held for more than a week. “She had control over the surveillance video.”

LoTurco insinuated that Pollina was manipulative.

“Michael Valva really was meek,” he said. “He was passive in the responsibility of the children — that she controlled the children. She actually controlled Michael Valva himself.”

The former lovers each face second-degree murder raps for allegedly forcing Thomas, who had autism, to sleep in an unheated garage when the temperature outside was a frigid 19 degrees last year.

He was found dead the next day.

His younger brother, Andrew, 6, previously detailed how he, Thomas and their brother Anthony, 10, were allegedly abused by Valva and Pollina — saying they were often tossed in the garage as punishment.

Meanwhile, Pollina’s lawyer Matt Touhy accused her former beau of killing Thomas.

“What my client is saying is that he unequivocally is responsible for the boy’s death and she’s not,” Touhy said outside court.  

In court earlier Wednesday, Touhy ultimately decided to not allow Pollina to testify in the pre-trial hearings — despite her wanting to take the stand.

During the hearing, Judge William Condon asked Pollina whether she agreed with her lawyer’s decision.

“After carefully reviewing the risks … he has made the tactical decision not to call you as a witness. Do you agree with this decision?” the judge asked.

“Yes,” Pollina responded in a clear voice, her once-long brunette locks now gray. 

A more weathered-looking Valva sat across from her but the two didn’t appear to look at each other during the proceedings.

Prosecutors claim the boy died of extreme hypothermia and that surveillance videos captured him shivering in the cold. 

The defense lawyers have already filed motions to sever the cases — hoping that each of their clients will face a separate trial.

The next court date is scheduled for June 17.