The first thing you should know are the 3C's:
You didn't Cause it.
You can't Control it.
You can't Cure it.
His drinking and his drugs are his problem, NOT your problem. You have no obligation to ride this roller coaster with him.
Unfortunately addicts are not known for seeing help until they hit some sort of bottom, and some have to fall lower than others before they start looking for help. Also, an alcoholic needs some sort of program. It does not have to be AA/NA, as those programs don't work for everybody, but it has to be something, and relying on "your help" or doing it "for you" is just more attempts at manipulating you to stay, feel responsible for his bad choices, and try to dig him out of it so he doesn't have to hit his bottom and can keep drinking in peace.
Don't worry about long posts, or ranting and raving, or anything like that. All of us have been where you are, and many of us are still there!