Emma, the only alternative to leaving him is this:
Print out that post you just wrote and hand it to him. Tell him that’s how you see him.
Tell him he MUST get counselling or you leave.
Tell him he MUST pull his weight in the household (write a list of ‘fair tasks’) or you leave
Tell him he MUST do more child care (again, write a list and a rota), or you leave.
Tell him he has six months to get off his self-pitying backside and man up, or you leave.
Tell him you’ll go to joint counselling with him, including marriage counselling, and if he doesn’t agree, you’ll leave.
Can you talk to his parents openly and honestly about the idiot he is? After all, they raised him, they are responsible for him.
‘Not taking responsibility’ seems to be his mantra. Not acceptable.
You may well love him, and he may well love you - but right now he is utterly unfit to be a husband or father. Or even a decent human being.
You said so many ‘honest things’ about how ungrateful etc etc mental illness (IF it is that, and I REALLY doubt it!), and that appalling sense of ‘entitlement’. You can SEE what he is. But don’t indulge it yourself.
The MOST important person in your life is your son. HE deserves a decent father. It isn’t hopeless for your husband, and he CAN man up etc etc and learn to be a decent human being and a good dad, but if he won’t (and it will be a question of ‘will’ or ‘won’t’ not ‘can’ or ‘can’t’!), then to be honest, your son is better off without such a bad influence in his young life.
The kindest thing to say about your husband is that he is as he is because he is ‘afraid he is useless’…but again, the only way to disprove that fear is to BE ‘useful’. And that requires effort, and not self-pity.