OK, so I just joined this group after intermittently lurking on this site for a year.
So glad you decided to speak up and post! Great to hear from you!
it's almost arrogant to take such responsibility for another person's feelings and actions.
I also struggle with taking responsibility for the actions of others. Counseling helped me realize that taking the blame for everything is a defense mechanism, a form of control. Releasing the desire to control means allowing others to take responsibility for their own actions - I try not to apologize for their behavior, I don't defend their behavior. Sometimes it just means staying silent when they expect me to pick it up for them.
To be clear, she's never been formally diagnosed. I'm not sure if she has BPD or not. I'm not sure if it really even matters.
Many of us here have family with undiagnosed BPD. I guess it can help to get a diagnosis but healing doesn't depend on it. Things can improve whether you have a diagnosis or not.
I also always felt guilty that I had such a superficial relationship with her. I avoid direct honesty about touchy topics because I know it will bring on an outburst. I think I have made peace with that somewhat now. I try and enjoy her company when the going is good and not engage too much when it isn't.
I have three daughters, and I would fully support this response to unhealthy behavior, whether it was my own or someone else's. You've developed natural boundaries to hurtful patterns.
Nothing to feel guilty about. I would argue that your responses to her, both your boundaries/limits as well as your engaging when it's good, is incredibly loving towards her. I hope you extend the same grace and love to yourself.
I do feel trapped with not having much of a relationship with my dad.
Whew this is the tough stuff, isn't it? When your relationship with a cherished family member is affected by a disordered individual? Some of it is simply grieving loss. Sometimes there are things we can do differently to alleviate the tension and drama. The Karpman triangle can come into play, have you read up on that to see if any of it applies? Check out the tools tab above.