Focus on you and your kid(s), both financially and emotionally, as if you were still single right now.You are entitled to do whatever you feel like to do to benefit your own life.
If he senses the change and confronts you about it, or you want to initiate the conversation with him about it, be honest and straightforward and tell him your concern and uncertainty.
If he takes actions to improve himself, then stay with him. Otherwise, leave him. Being single is way much better than being with a wrong person who keeps making you wondered and even suffered. And only when you leave the wrong person, the right one may have the chance to run into you.
I have to patch up some work now. Good luck and best wishes!
