IMO, you may need to arm yourself better if and when you do decide to leave this time around.
- where your son is concerned, a visitation schedule needs to be established from the get-go, and can thereafter be negotiated through legal representation or mediation. I'm not sure whether you would want supervised visitation or not, but again, I would suggest deciding on this before you make a move This way, your son gets to see his father on a regular basis, but you also give him the gift of a SANE and STABLE home with you.
- where your strength and resolve are concerned, I would suggest finding an Al-Anon group you feel comfortable with *as well as* individual counselling, be through a therapist or social worker (got mine through my work's EAP). I would also recommend reading "Codependent No More" by Melodie Beattie.
- where finances are concerned, I would have a budget laid out along with a reliable source of income BEFORE you move out. Financial need has often been the downfall of many attempts at separation.
I understand the desire to "help" him and "be there for him", but clearly, the man was alive and capable before you met him, and he will be after you have left. He may well have to learn how to fend for himself a bit better, but then, would you deny him the dignity of discovering how to do that for himself?
Furthermore, if you think that you have the power to keep him from drinking himself into the grave, I'd venture to say you're mistaken. You simply do not have the power to make him do anything...and sadly, alcoholism is a disease that if left untreated ends in death. Do you really want to be there when things get that bad? Do you want to bring your son along for that ride? Doesn't he deserve to grow up in a normal house, free of the madness of addiction?
IMO, It is not your lot to stand in the way of your AH's obviously self-destructive tendencies...
As for your need for him to "understand", well, to be honest, that may never happen. I too wished that my XAH understood that I was leaving him because I refused to go down in flames with him, and that I refused to subject my baby girl to it as well. He never did understand and in his eyes, I am probably the most Evil Woman That Walked The Earth. Can't change that. Other people's opinion of me is truly none of my business.
*hugs* to you. Keep posting and reading lots.