I think that's a bad idea that you want to get her professional psychiatric help and you want to report her to the police. Very bad idea. You will open up a whole can of worms, are you really ready to deal with all that? She could very easily make you look like the bad guy. Very easily. The police won't know who to believe, except her parents who say they came down the stairs and saw her nose bleeding and guess what? You just got in trouble for domestic violence. Leave now and don't look back, because by you trying to get her help, or trying to get the police involved, only tells me you want to keep being in her life somehow. Not a good idea at all.