ended my 5 year relationship

Soooo I saw a video on social media of my fiancé (of 5 years) dancing with another girl out night clubbing. These last few months have been rocky with him not helping with our 2 kids and other trust issues .. after seeing this video I immediately went nuts and ended things with him. It wasn't JUST the fact he was dancing, it was just the icing on the cake. He thinks I've made the 'wrong decision' because he doesn't see his wrong with what he's done (another big reason we've been having problems) .