Talking with a girl on Facebook and she's threatened to kill herself? Among other issues?

[Xysa Zing]

I met a thirteen-year-old girl about three weeks ago at a club and she told me the following day she had a crush on me. I said that was OK but I wouldn't enter into a relationship with her because of the age difference (I'm 17). Ever since she has been posting love messages to my Facebook wall, asking for my mobile number, etc. I told her there was no prospect of a relationship and she confided in me about being bullied at school for being a lesbian. She said she was thinking of killing herself and I'm talking to her now trying to make sure she doesn't hurt herself.

She also said something about one of the teachers at school comforting her after she walked out of class and the teacher resting her head on her and having a crush on her? I don't know if she's making it up to get attention or make me jealous, but I'm really not comfortable with the things she's telling me and I don't know what to do about it. I don't want to get her or the teacher into trouble if it's not true but I really don't know what to do. She won't change schools because of a disabled friend who relies on her, but she's being beaten up, having things stolen from her, and her finger's been broken by these bullies. I really want to help her but I don't know how.