I dated my xabf for about 8 months. When I left, I told him the truth. I told him that he needed to focus on getting himself well, that the pressure and stress of a relationship was obviously not helping (he more than once told me he drank because we fought, e.g. whenever we got into a fight, he was so stressed out he needed to drink), and that because he was struggling with addiction, he was not able to be there for me, which was causing me to suffer and hurt. He told me that his addiction had nothing to do with me, and he was right. Since it had nothing to do with me, it was important for me to stay out of it. So I did. I'm staying out of it.
Good luck.