You are just frustrated because you have been through a lot of stress and difficulties with her in life. You were always there for her, and under extreme stress, you are cracking up. Sometimes, we never get the answers that we expect to get and when we see all the efforts we have been doing and still do, it just feels like fighting a lost battle and that we might as well raise our hands in surrender and say "Enough, I give up!"
What more to tell you, except that you be strong.