Lvs, I understand your intentions are good, but please don't do like I did and try to educate the professional mental help professional who is dealing with your Husband's therapy. Not only are you pegging yourself as a "fixer" but you're attaching yourself and entering into his therapy- violating the boundaries of the therapist (it's getting crowded in there with all these personalities to consider; family of origin as well... .)
I had to learn this the hard way. This was a battle with myself. By letting go of my malignant optimism and concern that I could control the disorder, I was able to concentrate on my own reasons for my fixing behaviors, which ultimately were an excuse for not taking responsibility for my own wellness. I figured that, if I was involved, I was needed, I would be valued and subsequently loved. Now I understand the difference between loving to be needed and needing to be loved.
Some excellent points here, 2010. When I was still trying to work things out with my (now) X, I felt much of the same frustration. He and I went to 8 marriage counselors and he lied like a rug in each one -- in fact he got better and better at it.
Somewhere between number 5 and 6 I think, finally he decided (thank Heaven I thought) that he needed to see a psychiatrist, he "wasn't thinking right". And the acting out got worse and worse, stranger and stranger at home. The Doc would have nothing to do with me, even to listen to me for the details after X was hospitalized and the Doc couldn't be reached. It was a Memorial Day weekend as a matter of fact, and the Doc hadn't left anyone on call.
I was convinced that there was no way the Doc could have been getting the full picture about X. Finally in desperation I recorded a letter to the Doc and to X, that I asked that they play at the appt. Which they did, and according to X, the Doc's reaction was to say "well, she's really angry at you, isn't she."
(For a final weird twist to the story, X admitted to me AFTER I TOLD HIM I NEEDED TO LEAVE THE MARRIAGE, that he had duped the psychiatrist. I don't know what those details are and the further away from it I get, the less I want to know.)
I'm sure that it wouldn't be appropriate or well-received to try to inform a mental health professional about the subject of BPD, but they might be receptive to details about your interaction with your S.O. -- but to what end?
2010 raises a good point -- is your objective to give it one more shot or to leave? If to leave, then, yes, it's time to let it go. Sad I know.