You are my kinda guy, DCB. Intrepid. Focused. Determined. Prepared.
My hat is off to you!
Puppy
I have disrupted the comfortable nature of her A, even though MIL pretty much continues to enable - the cat is out of the bag and it isn't a secret any longer.
I have debated the "truth dart" technique you shared previously, and other options include letting OM's on again/off again girlfriend in on the A, but I'm not sure if that would solve anything or not. As far as 'exposure' her boss knows, our preacher knows, MIL/BIL know. Otherwise, I haven't shouted it from the rooftops. I feel it is an important bargaining point with her and her immediate supporters, because they are concerned about W's image.
Read some books on BPD and boundary-setting is an important part of reacting to behaviors. But transitional-A's are also a part of it, so as long as she feels like she has her white knight waiting on her, she won't do anything to consider working on the M as we march (ever so slowly) to D-day.
Also... I can't make her seek help. I can force the diagnosis, but after that I'm focused on D1 - not W. W is going to have to make the case to me, especially after running me several thousand dollars. I care enough about myself not to allow the inappropriate behavior to affect me and my children.
"You can't reason someone out of a position they didn't reason themselves into."