Your husband's antics and the toll it's taking on you are all the more reason to divorce him. I know it's hard to just end a marriage, but you really need to think of yourself and your mental wellbeing first and foremost. Clearly being with him isn't working anymore. Also, all this indecision is bad for your son. What kind of example would you feel your setting for him by showing him that you're not strong enough to take care of yourself?

Yes, I think a divorce is the solution that needs to be done here. You've done more than enough to try to save this doomed marriage. It's time to finish it once and for all.