Hello WishIwasNora and
40 years is quite a long time to be coping with BPD in the family system; I imagine you and your sister are exhausted with the disorder.
And, beyond the exhaustion, is the grief, like you mentioned. Grief and powerlessness are really difficult feelings to feel. My husband's kids' mom has many BPD traits, and I can relate to feeling so, so powerless in the situation, even though I'm not really in touch with her. Because, like you, I see the effect on the kids and other family members.
This seems like a wise choice on your part:
So she and I grieve. We love each other so much. She and I have never ever had fights. He tries to turn her against me, but she's at least wise enough not to let him fully succeed. Yet she stays with him, always stayed with him, and will stay with him. There's nothing I can do. I long since stopped urging her to leave.
Letting go of trying to change her and her situation (even though you may have urged her to leave out of your love for her) may help her feel like she can really rely on you to hear her and not judge her. Having one relationship in her life where she feels truly heard and not judged may be just what she needs right now, even though it may be difficult for you not to urge her to leave or make change.
Yet how to deal with this grief and feeling of powerlessness? I have no direct contact with my b-i-l, and never plan any, but his abuse still reaches me, as well, by seeing it hurt my sister and depriving us of a proper sisterly relationship.
The grief is real, even though your sister is alive. I wonder if you're grieving the loss of the relationship you wanted to have with her, and the life you wanted her to have. Those are real losses.
My therapist is suggesting I grieve what I have lost over the last >10 years: I've lost a peaceful family life and a normal start to my marriage, among other things.
Have you considered therapy or counseling for yourself, to process what you've been through, and to uncover and feel those feelings in a safe environment?
These are such hard family situations; we definitely understand and we'll be here for you.
kells76