I have been told by my therapist that it due to my daughter feeling abandoned when I was in the hospital for 6 months. It was not intentional abandonment, but I have so much guilt that my precious daughter suffered.
Hello and welcome to the family. My heart breaks for you in that I've had many of the same experiences with my BPD daughter.
First, I wanted to touch on what you shared above. Please understand that this is not your fault, none of it is. You had three daughters who processed this tough time and found understanding, while a fourth child still struggles with it. If you were a terrible mom, you'd have four kids resenting you...not just one. And i hated to say it that way but hopefully it speaks to you. You didn't fail and you didn't cause this.
For your BPD daughter, finding a therapist for her is not the answer here. If you can, sure, make a recommendation. But your kid is not going to get better until she's personally willing to change something deep down inside of her that's blaming anything and everything for how her life turned out.
She suffers because she's mentally ill, but refuses to accept that the changes she needs must come from within. That's the battle here, and it's not one you or anyone else can fight. She has to realize that on her own, in her own time.