You are approaching this the wrong way, as you cannot help someone who doesn't want to be helped, or isn't willing to help himself. To be frank, you enable his behavior rather than help it by supporting him no matter what.
Now live your life and let him get his own motivation, and maybe losing you is the best motivation for him to do better, by paying the consequences of his own actions. This cannot be a healthy love because he is not healthy himself, and honestly you are feeding into this the more you cling to him.
He needs to make better choices without you. Not just to keep you.