A spurned ex broke into his former girlfriend’s Queens home using a brick, then threatened the woman and her son with a meat cleaver, police said.

Damion Jackson, 41, smashed the fire escape window of the Astoria apartment near 24th Avenue and 31st Street about noon Sunday, then threatened to kill the woman, 39, and her 24-year-old son, cops said.

After terrorizing the two, Jackson put down the weapon and fled the apartment on foot, authorities said.

The mom and son were not injured.