Hi Btyjc8002,
Welcome to the site, I'm glad you reached out and feel comfortable sharing with us. It's helps to have peer support and know you aren't alone.
Has your D been diagnosed with BPD? Do you have anyone else in your family? Siblings? If you have a spouse, how are the two of you coping with your D's behavior?
How did you get your D to the hospital?
I found Blaise Aguirre's book about BPD in Adolescence to be really helpful -- there is a second edition out now that has updated information. He is adamant about diagnosing BPD in kids and not waiting until they are 18, which has been the common practice.
I also remember he wrote that if there is only one takeaway from the book, let it be about validation. Has anyone mentioned this important skill to you? My son (13) was diagnosed ODD, ADHD, then anxiety/depression. The jury is still out about whether he will follow in his dad's footsteps and develop BPD, but I am at least certain he qualifies as a "highly sensitive person" (HSP). I feel that validating his experience is what helped minimize the conflict in our home and has helped him develop a stronger more stable sense of self.
Here are some good resources about validation that I found helpful, especially the one about validating questions. This helps put the problem-solving back in their court so they have some agency:
Hang in there Btyjc8002! I know it's hard. It does get better, though. There are tools and lessons to the right in the sidebar that have helped me understand so much of this awful mental illness. Knowledge really is power
There's so much more to share! I feel this is a good starting point, and others may have some ideas to share.
LnL