not so sure anymore

I am not so sure I want to live anymore, I am so sick of all this. I relapsed on my eating disorder about a month ago and I don't know how to tell my parents. I don't want to let them down, but all I keep thinking is how HUGE I am. I really don't want to live. I keep remembering all these times when I was just so horrible to people I am supposed to care about. I don't know if I can live with myself anymore. I really hate myself. Now as well, my little sister tried to cut herself. I think it was my fault, I mean I could have exposed her to it. What if she starts to get and Eating disorder too?? I don't think I could live with that. I just feel I need to get Myself out of their lives before I ruin them more.