Hope, I understand how you feel. My husband has been sober a year, and things are still not good. I am questioning whether I want to stay or not. We do not live together, as I didn't want him coming home after rehab. So many times when I'm around him, I just don't feel good. It is as if he is pulling the life out of me. I realize I am responsible for my own happiness, and I have to draw my own boundaries when I feel like that.
Yesterday he came over, and was in a funk. After a brief chat, I asked him to leave. I told him that I could not feel good and be around him when he was in that negative place, and if he couldn't pull out of it, I didn't want to be around him. I had a good day after he left.
As for leaving for good, I believe that I will know when it is time to get a divorce, if that is the course I will take. If you haven't read it, or read it lately, I recommend Melody Beattie's The New Codependency (or something like that). I read it when my husband first entered rehab, but it had a different impact on me when I read it again months later.
Good luck.