Yes, that kind of violence can be part of BPD (this is why most males with this diganosis end up in jail) and yes it can be diagnosed quickly in some cases. Anger and frustration are a big part of BPD.

What was the recommendation of the doctors at the hospital where she stayed 2 weeks? Is she following through? Is the family willing to see a family therapist? The family doctor may be nice, but this is way beyond his scope of practice. I hope you will continue in therapy to help you deal with her when she is threatening. I hope you can establish a zero tolerance where she understands she will be asked to leave immediately or you will call 911 when she begins to show any kind of threatening or violent behavior. Then do it. You may have to do it a few times before she believes you. Then the ball is in her court and she decides how she will behave, knowing exactly what consequences threatening and violent behavior will always have for her, with regards to you. BPD is not a free pass or an excuse for unacceptable behavior.

If a 22 year old needs a new wardrobe, a 22 year old can buy one herself. Sounds harsh, but it's meant to ask, what is she doing for herself? Is she working? Is she working toward and independent life?

She's just really too old to be playing Mom against Dad, and I think she'd feel so much better if she was planning her own independent life, but she'll need to get her behavior under control first and DBT therapy can help her do that.

What would she say about her life, about her behavior, if you were to sit down with her at a quiet time when she is in control of herself, and no one is judging anything. What direction would she like her life to go? What fears keep that from becoming a reality and the good news is that therapy can help with those fears and help a person make those goals materialize.