The counselor flatly stayed that only a professional can diagnose BPD. I told her that he'd be a different person in front of her. She replied, "Oh, I can tell a borderline in front of me."
Sounds like you have an experienced counselor. It's true, despite your years of living with your spouse, you are not considered trained and qualified to make a diagnosis. I faced that officialdom position too. I spent two years in divorce and six years afterward in and out of family court seeking a court order that worked. When I finally attained that goal after eight years, the magistrate wrote in the decision that my ex needed counseling but declined to order it because maybe the ex couldn't afford it.
You may have to content yourself that you've discovered or confirmed for yourself why - Borderline traits - your spouse acts the way he does. So many arriving here had just learned about BPD traits, the perceptions and behavior, and had for so long felt like they were dealing with an unseen and inexplicable foe.
Most of us here never got a diagnosis, or at least we never got documentation of one. In family court it seems a diagnosis is not as important as one would think. Instead, courts would take a position that a diagnosis in itself does not indicate how that would impact a marriage or parenting. So some of us with minor children have had to request Custody Evaluations, more in-depth than a mere cursory Psych Eval.
Courts instead rely on documentation and evidence, as appropriate. You don't have to prove why you decided to divorce, court is more than willing to referee the process to ensure it gets done if that is what either spouse decides.
If you haven't already, start a private journal, diary, or similar to document abusive or poor behavior so that you can have sufficient details of the incidents to support your statements. Vague claims like "he always..." or "she always..." is considered hearsay and mostly ignored.
In some areas destruction of property is considered abuse and actionable. Ask your local professionals for legal advice and strategies.
