Hi.
It seems you want to seek help regarding your anger outbursts and depression. Though the last part of your question is not very clear, I guess you are still emotionally involved with the girl. Do not take her ignorance as a sign of your own weakness. She may have her own priorities. Do not let someone become your priority when you are just an option for them.
It may sound boring, but talk to you parents! They are the best people you can talk to in present situation. Explain to them how you feel about all this. Do not get biased towards a negative response from them.
Additionally, I would advise you to seek help of a therapist for a few weeks. You may be carrying a lot of bottled up emotional conflicts, which need a way out, not in the form of violence, but some constructive actions.
Regards
(This post is for the purpose of providing medical information and is not a substitute for a face-to-face consultation with a doctor. This post is not intended to give or rule out a diagnosis, create a doctor-patient relationship or replace an existing one.)