FF, I think you may be right about joint C. If he goes in there on his best behavior (what does that look like, BTW?), it may take many sessions until the C can see who he is. And he could very well use whatever he finds out to make your life more unpleasant at home. Usually C only works if both parties are willing. I like the idea of C as a haven for you-- a place to vent safely. Does your C know you are contemplating leaving him? Does she know how the laws work around there?
When my bf was drinking I read a board for families of alcoholics and I used to think often: "Well, at least he doesn't do THAT!" It helped me with my sanity, but it sure didn't make him any easier to live with.
When I would read about the stuff that some alcoholics did, like passing out in the front yard, or not coming home for days, or spending every bit of money on booze-- and the women (usually women, not always) stuck with them year after year, I would say to myself, "If he did those things, I would SURELY leave him!"
As it was, fate intervened, and he had the heart surgery. He was thinking that when he got out of the hospital, he would be one of those "glass of wine a day" people. At that point I KNEW I couldn't be with him if he touched another drop of alcohol. Something in me just snapped. I would be watching every night to see if he had more, I would feel like I was being kicked in the head every time he came home with that big brown paper sack. And I had no trouble saying to him-- while he was still in the hospital-- "I cannot be with you if there is any alcohol in the house." I may have only said it once, I don't remember. But I meant it with every fiber of my being. And he hasn't had any since (we did share a bottle of sake on my birthday at a sushi restaurant). (He is very proud of himself that he is facing all this job stuff with NO booze-- and he has said that he feels it calling to him, but he is committed to staying sober.)
I guess what I'm getting at with this story is that one day, something will happen, probably something small, and a big light bulb will go on over your head, and you will know with absolute certainty what you must do, AND you will do it without hesitation. You're continuing to work on yourself, to go inside and check your feelings, seeing the C-- do you pray? Praying might be good-- not praying to God to fix the situation (I don't believe in that kind of prayer), but praying for an open, aware heart and mind, so that you will know what to do when it is time to do it.