Is she my responsibility now? i don't know what to do.?

allrightg, i have known this girl for half a year now. she has always been pretty messed up, bad past, she does alot of drugs, she is a good person, but she is very negative, and like, very broken. she doesnt love herself, and she does not think other people should love her either. she h attempted suicide twice (that i know of) and although she has always looked for love, she has made bad choices and always wound up getting hurt even more. I talked to her for a bit, and I realized that i was being given the oppurtunity to help this girl. so i told her that i was a hundred percent here for her, and that i really care about her, and will do what it takes to help her. she told me that she finds it hard to believe what im telling her, and that she thinks if I knew more about her i would stop caring and leave like everyone else. i told her to try me, because i knew ( and still know) that i will not stop caring about her ( im very christian, and so its my responsibility as a christian to do my best to love others unconditionally.). i would paste he message she sent me on here, but it is like a page and a half long and noone will take the time to read that. so ill give you the gist of the message. she said when we first started hanging out she knew i was special and that im growing more special to her everytime we talk. she told me she will be a negative influence on me and does not fit into my life or plans. she said that i make her smile so much her cheeks hurt, and laff so hard her stomach sometimes hurts. she then asked me not to judge her for her past, which i said I wouldnt. so now that she has told me about herself, I know that i cannot leave ( i dont rly want to, ill get to that in a minute) because if I did it would affirm everything she already thinks about herself. i understand that. and I really do want to help her, I want to be there for her, and be the one who gets her off drugs and back on track in life. but at the same time, this relationship will be mively draining on my part and it will take alot of strength to not fall into the negativity she has. i realize i have taken the responsibility of helping her now, and I am not really sure what I am asking you guys here, Im sorry. i just want someone to tell me something that will help me. thank you for your time.