J.E.
I am so sorry you're going through this. It sounds like he's an addict who can't take care of anyone else right now. He's completely focused on his addiction. It sounds like you're enabling his behavior at this time. Has he tried to get help? Does he want to quit? Or is he completely lost in the addiction?
Think of it like a bullseye. His addiction is in the center. He circles around the addiction and can't look anywhere else. You and your children circle around him. You can't fix him. He needs to get healthy. You and your children deserve that. Go to an Alanon meeting. You need to take care of yourself and only then can you really care for your children. You need to break away from the cycle.
If he's not willing to try and change, you need to decide how long you can continue this. It's affecting your health. I'm not trying to sound harsh, but your family is already broken. He is the only one who can fix that by making serious changes.
Good luck! You will get through this, but you will have to make some changes for yourself.