I know when I feel like that its usually because I feel guilty (inappropriately) because getting my way doesn't so much feel like the right thing so much as I got something at someone else's expense which then triggers my feelings of being like my abuser. So even standing up for myself and getting the other person to listen doesn't make me feel better, even though its a perfectly legitimate. And feeling like that leaves me confused. I'm not sure if this is true in your case but I just wanted to offer it as a possibility for you to try out and see if it fits. But you have my sympathies, family is hardly ever easy or simple.
AG