Puddinface, you are not alone. So many of us on this board have been exactly where you are, and we know how painful it is. You're right - you can't fix him. No matter what you do, it rolls off him like he's made of Teflon. You try love, anger, bargaining, threats, bribes, and nothing, nothing, nothing works. Every day, you are working harder on his recovery than he is, and you realize that he is not working on it at all.
You have to let go. It accomplishes nothing positive for you to allow him to destroy you along with himself. He's going to do what he's going to do, and you can't control it. You can't even influence it. Let go. If he finds recovery, it will be because he chooses it, and it will (or won't) happen in its own time, no matter what you do. It's time to refocus your attention on your own life and to take care of you.