A Brooklyn judge yesterday ordered a mother embroiled in a bitter custody dispute to cut back on all the FaceTime with her 10-year-old son.

Fordham law Professor Annemarie McAvoy was ordered to take away the boy’s iPhone because she was using the Apple device to pry into the father’s home — spending long stretches talking with their son via the smartphone’s FaceTime video-chat feature.

“I believe the mother has entered the father’s home and has taken up residence to a certain extent,” Brooklyn Supreme Court Justice Jeffrey Sunshine said.

He told her to replace the high- tech device with a simple flip phone to stay in touch.

McAvoy had maintained that her son was suicidal and needed to be with her, while the boy’s father, real-estate investor John Hannigan, felt the mom’s claims were exaggerated.

Sunshine agreed, leaving the boy to live with his father in Sparta, NJ.

McAvoy, who plans to pursue a federal civil-rights case to get custody of her son, said she used FaceTime to help him with his homework and taking it away would only “punish the child.”