Unfortunately if someone doesn't want help or want to live you can't make them. My brother and sister are self destructive and there is not a thing I can do about it except try to be there for them when they ask for it. It really sucks to have to stand idly by and watch someone wither away. Basically you have to watch someone drown with your hands tied behind your back, and just hope that someone will reach them in time. I hate this helpless situation. I know how you feel.

Take care of yourself, I hope your friend heals soon.