TroubledSister, I have been the troubled sister, the troubled daughter, too. I sometimes still am. But one thing I have learned that has helped me immensely is I learned to put my self FIRST and everyone else after me. Yes, it still feels selfish when I do this with certain people. But I realize that is actually me feeling guilty about things that are out of my control. Especially with my Mom because she has struggled so much in her life.
But putting yourself first makes you stronger and better able to "help" those we love in non-codependent ways. At least that is what has been happening with me.
So take good care of your self.
And thank you for posting this because it is helping me.