Anorexic/bulimic Mum

I'm 18 in two weeks (Y) and we are having a family thing to celebrate. But I'm really worried about my mum. She's anorexic/bulimic and is addicted to exercise as well. She hates people (everyone) and she hates food and she is a recovering alcoholic too so family gathering, food and wine is not going to be a good combo in her books. Whenever we have a family thing she will lose shed loads of weight in the run up to it and then I will come back from school and she will thinner than ever which is an achievement anyway and grey. I've also just discovered that she is still prostituting herself, but it's not even her, it's her otherpersonality so I don't really had anyone to. Lame. I'm always so worried that one day she won't get up at 2am, that the amount of painkillers, laxatives, self harming and lack of food will be too much for her body one day and I will just find her on her bed not having women up - ever. It is on my mind constantly. She has already done 3 suicide attempts in the last two years and I know she hates her life. It kills me to see her look so miserable. I can't tell her that I know that she is still prostituting herself. Ecauss she would just start drinking again. I'm the only one that is really dealing with. My grand parents have given up and so don't deal with any of it anymore, my sister has got an eating disorder and I have a very bitter relationship with my father to say the least. I don't know what to do.