That it's not going to work - as you've been told already. You need to cut ties with this girl. Tell her you aren't interested in her and that you should stop talking to each other.
It's not up to you to fix her. You wouldn't be able to fix her, anyway. Her issues require professional help.
I know that you are loving the attention, but all you are doing by keeping her close is hurting her. Just so you know.