This poor girl is looking for love in all the wrong places and running from hope.
A great discourse and what an unbelievable story Shaula, that's quite the show of selflessness and love, I'm very impressed. I'm reminded of Boone and Shannon on LOST.
I resonate with a lot of the problems everyone is bringing up, and I have to side with Evan on this one. Show kindness, love, care, support, and continue to be her emotional rock and her soft place to land only if she's receptive to you, but know that depending on her psychological state, your very involvement may have a negative affect and push her even further away and further into this downward spiral. You may be too close to the situation to help her. My advice is to seek the help of responsible people who can help YOU to cope Shaula, like your parents and her parents, teachers, counsellors, pastors, and other such responsible people that deal with these situations on a regular basis. You'll find that help isn't that far away. You can't go into this alone and be a martyr, as that too will only push her further away. Hope is the real issue here. She's abandoned hope and on a war path of self-destruction. If she's receptive to you, appeal to her heart and not to her head. She needs to feel that she's loved intrinsically for who she is. She needs to feel peace in you so if she is receptive to you, be gentle, be loving, be kind, be understanding, be supportive, and always stand your ground when she starts to attack you. Love her in her anger and rage, and know your own limits of what you can handle.
All of that is usually not within the INTJ (not saying that's you, Shaula), but INTJ's are more about putting a bridle on people and forcing them to listen, which is not going to work, and she may already see you as that person. Never lose heart or lose hope in her, and learn the limits of what you can do until she becomes receptive to you.