An irate man attacked his ex-wife’s boyfriend with a hatchet and fatally shot him in a jealous rage in a Brooklyn parking lot, police said Friday.

The 47-year-old ex-hubby allegedly flew off the handle when he saw the woman with her 42-year-old boyfriend in a parking lot on Ocean Avenue near Avenue Z in Sheepshead Bay just after 9 p.m. Thursday, cops said.

Cops found the 42-year-old lying on the pavement with the 44-year-old girlfriend at his side, screaming at her ex, police sources said.

The victim had been hit in the head with the hatchet and shot in the chest, cops said.

About six shots were believed to have been fired, sources said.

He was rushed to Coney Island Hospital, where he was pronounced dead.

The ex-husband, whose name was not released, remained at the scene and confessed to the attack, sources said.

Police found the gun under the SUV and the bloody hatchet in the trunk, sources said.

The ex had not been formally charged as of Friday afternoon.