hey, no you're NOT a horrible friend ur a really good friend for caring so much about her. I used to be severely anorexic myself and like ur friend, i could have been sent straight to hospital ( I think my bmi was 14 or 15 something). Even though she might not act like she wants help deep down she might because i remember when i was losing wait so rapidly i knew things were getting out control but i didn't know how to stop it, i just wanted someone to care enuf and interevene without been scared about how i might react. also, an angry friend is better than a dead one. interevening would hafta be planned carefully so it's a sticky issue which i don't know if i can say how to go about it so maybe talk to a counsellor or someone who has experience in dealing with this stuff ( as a professional, not first-hand like me!). But personally i think this is a serious situation and it is necessary. Good luck and pm me if you need anything more. She is lucky to have such a great friend.