I don't think you should feel responible for your friends actions. Be there to support her, but it is her choice on how she handles things, good or bad. Let her know she is cared about and you don't want to see her suffer. It sounds like your friend needs more help than you are able to provide. You are friend, but you also have your own needs and problems. Please don't forget yourself when trying to help her. Setting boundaries and not becoming depleted is part of a healthy friendship.