I think I am being physically abused and stalked by my girlfriend. What should I do?

stop being such a pu$$y and MAN UP. i do have sympathy for you, but any other man would have left her by now. she won't even let you breathe. If she's threatening to kill herself, tell someone close to her about this, a family member, close friend etc and leave them to care for her. she's trying to make you feel sorry for her and you fall for it each time. Good luck.