Sorry to hear your going through this sweetheart
Is there any way you can discuss with him the idea of rehab? (or better discuss it if you have already?) Could you tell his doctor about how things are rapidly deterriorating and see what he suggests? Sorry my advice isn't that great. I really hope you find a way of coping better - remember we're all here for you on PC. Perhaps you could get your brother to come and take a look at the addiction forum on here?