Welcome Gwammax2!
So very glad you've found a place where we understand! Thank you for sharing your story.

How hurt you must be, and the pain doesn't go away. I wish all could be made better in a very short time, but with a BPD, as you know it is tough. I am glad that you've gone to T, but have you considered going for yourself only, without your DIL? I would encourage you to get support for yourself from a T who understands BPD. The support I've received from my T has been beyond helpful, and life changing in being able to help me grow and understand the effects of BPD which I learned from growing up with an uBPDm.
From what you've posted, it sounds as if a lot of triangulation is going on. Here is a link to a workshop about triangulation, and a little ways down in the second post you will note the
Karpman triangle with another link listed there.
What does triangulation mean?Please take time to read as many other posts as you can, especially those dealing with in laws. I'd love to know what you think of the link when you have a chance to read!
Wools