Hi Releaseme
I am sorry you lost your dad two years ago. Losing a close relative is often very difficult for people. You mention your mother still grieving his passing, which of course is understandable. How have you been coping yourself? Do you feel like you've been able to grieve your dad's passing?
It's unfortunate what's going on with your sister and how this is also affecting your elderly mother. I can see how your sister overhearing what you said about her could trigger her. Was this the first time she heard you so directly express how you feel about her behavior?
1. She wields the defense mechanism of projection like a highly-skilled craftsman.
2. On one day, in her eyes, I could be the Second Coming of Christmas, and the next day I could be the Anticristo.
Projection and splitting, yeah that definitely are classic and textbook BPD behaviors... .well at least you got to be the Second Coming for a whole day
But on a more serious note, dealing with projection and splitting can be very difficult. How long have you suspected your sister might have BPD?
You mention her children not speaking to her for over 5 years, do you still have contact with her children? How would you describe the way your sister treated her children?
Take care and though your screenname is
Releaseme, I'll still add some hugs