I have a severe anxiety disorder and the worst thing someone could ever say to me is "just get over it". If you had cancer would you want someone to tell you to just get over it? Nope. Its the same deal. However, if your sister isn't getting treatment I understand why you are frustrated. She should be taking care of herself and pushing herself to get better. You can be there to SUPPORT her, but you aren't her care taker. It isn't good that her emotional outbursts are getting to you. If she isn't in treatment, could you suggest it to her? I think its good to offer support, but if someone refuses to help themselves, that doesn't mean you have to stay and take the brunt of what they are dishing out.