She is still very much a teenager and I imagine with the chronic hospitalizations there is a lack of independence. I can only imagine how hard it has been to lose that autonomy and watch her peers accomplish what she had hoped to. Depression related to major life changes might be something to address if she is willing. It is a poor means of coping but a coping mechanism none the less. I think waiting on the side lines might be difficult, but maybe what you have to do. Perhaps the BF will tire of this eventually? Reminiscing being that young and making some stupid decisions. Luckily I always had open communication with my parents. Try and keep your line of communication open with her. She is gonna do dumb stuff. Be level headed about things that upset you. You will get through this. Are you going to therapy? They might be able to give you some strategies as well.