once he's had 1, he can't stop - but he's not an alcoholic.
That right there is pretty much the definition of an alcoholic.
So let's see what you have here: A guy who gets drunk every night, who smokes weed, and who uses "white stuff."
My question to you is: How do you see yourself? What is it in your view of yourself that makes you think that he is a good partner? Why don't you think you deserve a decent partner who treats you well?
That's where I would focus my energy. Not on him. Because as others have said, you can't help him. Addicts are like drowning people, they'll drag you down with them if you don't watch out.