Emotionally abusive people typically promise to do better when faced with a credible threat such as you have presented him. Once the crisis has passed, though, these people typically revert to their abusive, cheating behavior.

It sounds like he has lied and cheated for years. What reason is there to believe that he has suddenly changed his entire personality?

Friends, family, acquaintances, logic, reason all tell you the same thing. What could support a decision to ignore the weight of all of those voices?