Wow, You're a saint to take on such a responsibility. I have three grown kids and there have been some serious challenges but not to this extent. All I can say is you can't take care of someone else unless you take care of yourself first. The relief from the booze is short lived and ultimately always makes any situation worse. This I do know from experience.
You have my sympathy but mostly my admiration. Wish I had some life changing advice I could give but all I can offer is support.
Please take care of yourself.