It is a hard position.
Instead of cutting your losses and leaving could you frame it, to yourself and him, that you are moving into your own space for 6 months and see where things go. If he continues with his counseling/recovery/abstinence etc. you can maintain contact and work on things during that time. At the end of 6 months you can take a look at where things sit. If he does not stay on the path to recovery, well then you have your space.