I'm glad you got to talk this out with your friend, that sounds so helpful, which of course it is.
Where you say:
somehow I know I have taken on the 'mother' role from the very beginning because of his drinking.
That's true. As you tell more of your story this is coming through loud and clear.
Even the comment last night: " yes he did think about drinking but that he knew he wouldn't get away with it so he didn't do it"
This is something a kid would say, not a grown man.
So are you controlling? Well probably, but you are not dealing with an equal partnership here. You are dealing with someone who is looking at you for clues as to what he can and cannot get away with. While you may be looking at your family as a "whole", I don't see him looking at it that way.
The only person, as is said often, that you can control is you. Now, that said, other people that you control to some extent are children. As you (very well!) know, that's your job and you keep them corralled as you teach them.
Well somehow he has wandered in to that corral. Now, does that make you controlling or is that just his role in this relationship/family and you have just stepped up to the plate.
chicken - egg
Doesn't really matter, it is still where you are at. Drinking aside, there is much more going on here.