I understand where you both are coming from. Honestly, I'm not sure what I would tell a friend if the story was their's, and not mine.
I would probably say the same thing as everyone else that you deserve better, and as long as alcohol and substance is involved, it will never progress. I think couple's therapy would possibly help too, but it would take a lot of work on both sides. Basically do what's best for them for once - like what everyone else is telling me.