The most useful thing is to stay out of it. He knows why he's in this position, and he may still choose to drink again. But you won't in any way have control of that situation. I know you want to 'help'; you can't. You're already supporting him financially, right?
You don't 'need' to be positive or negative, because it won't make any difference except to give him the impression you'll take on his burden for him.
My suggestion as a sober A, is that you allow him to work his own way through this. Have you attended Al-anon meetings yet? I'm sure you'll find lots help there from people who have been in the same situation.