Stop toying with this poor girl - you don't seem too interested in a relationship, but would be willing - with some approval (from the side lines ) - to pity **** her? Do her (and your 'morals') a favor - break it off for good - or get serious about finding it in your self to try to work with the difficulties and nurture the relationship - sex is easy - it's building and keeping a good relationship through tough times that's tough - nut up.
If you dont like her neediness you need to stay away plain and simple, if you get back with her you might regret it later on
Dude, why not stopping all this retarded, bullshit women want you to play. You don't want a relationship? It's fine. You still want sex? It's fine. You can use her, but it will bring social consequences. If you don't want to go against you principles as in moral code etc., just tell her the truth simple as that. Don't keep it ambigious, say you want to have sex, but you don't want a relashionship. She either agrees or not, but whether she will handle it emotionally or not is up to her. Don't sweat it, everyone is responsible for his own feelings, it's not your fault if she has some kind of attachment issues.
Do not get back together with her. She's just having an oddly hard time accepting the fact that it's over. You can be there as a friend but don't string her along especially when she has not yet bettered herself. If she hasn't changed who she is then you'd be going out with the same person that you just dumped and you'd want to dump her again. No fun and you'd get a bad reputation. I would wait to date for a while (till you think it's right) so you don't rub it in her face more and keep the flirting down if you can. But don't stop being friends with people. You can still care for her and help her without being her boyfriend. She might need some space. Try to get her to hang with her other friends, maybe ask them to take her out to a movie or something. Don't go overboard to help her though. Clearly state that you are not trying to 'work things out'. That will give her false hope. If anything, just ask her friends to help her or her parents if needed. Maybe the school councilor if she is lacking friends. Drinking to release the pain isn't a good thing to do no matter what age.
I think if you do anything with her, you're going to give her mixed signals of your intentions and she may think you're more into it than you are, it sounds like she's not someone you want to be with, so if you find yourself back with her, you'll only want out again. I keep a distance until the emotions aren't so raw between the two of you.
She seems very emotional right now, and she's already attached to you. If you hook up with her that's just cruel, because you're leading her on and making it impossible for her to get over you. Either be with her or don't. It's not right to leave her hanging somewhere in the middle.