A Harlem dad who beheaded his wife and murdered his daughter before killing himself had issued a dire warning that he was not going to “lose” a bitter divorce battle.

All three — wife Jennifer Schlecht, daughter Abaynesh and husband, Yonathan Tedla — were found dead in their apartment Wednesday night.

Schlecht, 42, had planned to get a court order to keep Tedla, 46, away from her and the girl out of fear for their lives, the tragic mom’s father told The Post.

“She wanted an order of protection due to some of his threats,” said the father, Kenneth Schlecht, 75.

Tedla had threatened that if she tried to divorce him, he would win and she would lose.

“He’d destroy her, or take them all out if she pursued a divorce,” the father said.

He believes his daughter had hoped to get a protection order on Tuesday, but found the courts were closed for Election Day.

She was found dead with her daughter inside their second-floor apartment the next day.

Law enforcement sources believe Tedla decapitated the mom with a knife, then slit the girl’s throat before hanging himself from the girl’s bedroom door.

Schlecht, a career humanitarian who fought to protect women and girls in poor, war-torn countries, was found on her bathroom floor with her own head lying in her lap, sources told The Post.