That’s awful and riddled with issues you can’t resolve without professional help for him. Will he attend the doctors with you to discuss this ? (make a double appointment).
We are not machines, things can change for the better or worse yet probably won’t. I don’t want to appear sexist yet the divorce and family court system is heavily rigged to support mothers at all costs. His documented issues will certainly go against him too. I say this to hopefully help you feel you and your son will be ok, you’ll probably keep the home, have residency of your son and receive Universal Credit if struggling financially. It could be so much worse for you as it is for me in my current situation facing the loss of my home and risking my relationship with my youngest and the only child of 3 not alienated from me.
Keep your chin up at all costs, you and your son will be ok and support for mother’s is all around. If things head down the divorce route keep in contact with him but be VERY careful, hopefully your son will grow up knowing his father yet look after yourselves first and foremost.