Those who have to "out-crisis" or "out-trauma" everyone around them are exhausting, Conni. I don't have any of those in my family, but I know them well enough. I'm sorry that you have experienced this from someone so close. Your decision to let her go seems quite right.
I agree with Michelle: I've always thought that adults accept the responsibility for themselves. Many of us realize that we inherited tendencies, ideas, and habits that are detrimental to our best lives, but we fault (and hopefully change) those inheritances, not our parents.
All best to you, my friend.