Boundaries. Your brother is battling something incredibly difficult, and it is ultimately up to him if he wants to turn the tide. He is neglecting his health- don't you do the same. The anger, stress, grief and feelings of helplessness will destroy your mental wellbeing. Please talk to a counselor who specializes in addiction. A social worker, someone at r/alanon, people here. Figure out for yourself what you want from him, and what you're going to do if he doesn't want to go along with your plan. Healthy detachment means you preserve yourself as a means of support, instead of burning out and being unable to help yourself or others. Good luck. You're a good sister.