A former Kendall bank executive who gunned down his ex-wife’s unarmed husband, lost his bid at immunity under Florida’s controversial self-defense law.

A judge Wednesday rejected Cristobal Palacio’s claim that he was defending himself against Paul Winter, who was shot six times — including twice in the back in October 2008— as Palacio’s 7-year-old twins watched in horror.

The judge’s ruling means that Palacio, 46, will face a jury trial next week for first-degree murder.

Palacio and ex-wife Jennifer Winter had undergone a bitter divorce that culminated in September 2007. Afterward, she married Paul Winter, a British-born graphic designer she met online.

Palacio claimed Winter spent months tormenting him, twice putting a gun to his face and frequently using profanity against him. The confrontations, Palacio claimed, took place during custody visits.

But Jennifer Winter testified Wednesday that her husband never owned a gun and was a peaceful “nerd” who avoided conflict. She also said her jealous ex-husband blamed Winter for their breakup.

Paul and Jennifer Winter had gone to Palacio’s home to drop off the twins for a week of court-appointed visit. Palacio claimed Winter charged at him in the driveway, reaching for what appeared to be a gun.