Hi bpbreakout,
Looks like she has also learned about boundaries and is trying to use them to control you
Just interested in what why you think this
You are clearly very unhappy. Luckily for you have the support of some very good friends and a couple of very good psychiatrists, I would make the most of them and start following their advice with regard to your anger and control issues which are destroying your relationships with everyone in our family. I would be a bit more open with other people about your failings rather than trying to paint everyone around you black. Of course you are an adult and it is entirely up to you what you do about this and unlike our daughter I have no responsibility for you in this department you can make your own choices.
"I take not the responsibility for your happiness" is a boundary inspired message. There was another post of you where you describe her closing her ears with her hands and is leaving the discussion - the point here is she is controlling herself vs. the alternative trying to shut you up with escalating force.
It looks like she knows some aspects. Not all is healthy - she is mixing controlling messages in between - everyone is responsible for their own issues (good) but I tell you that you got to fix your by this time or else (not so good). I guess the really hard part about boundaries is to stay on your own side.
Neither side is using boundaries to control themselves
Interested to know whether this means me and BPDw or D15 and BPDw.
It looks like your wife feels pushed to justify herself:
Thank you for this email and your demand that I either believe either your version of events of that of my daughter.
You have asked me to make a choice and I am clear on where I’m at with this.
the alternative is
Live your values, BPDbreakout, while communicating that they are yours, not supposed to be hers.
has a lot of emotional investment in having "difficult" children and an "un-supportive" partner
Knowing that to validate it should be easy. It is her right to consider you un-supportive and her D difficult. There are plenty of mothers who struggle with their teen D's. No need to do much about it

Telling your wife that she perceives that D is acting extreme is validating and can be ok. It is your right to have a different opinion too - often no need to express it and seldom a need to come to a common understanding. Consistent parenting is important but with D being 15 years old and your current situation that will have to take often a backseat when it comes to expressing something. Now when it comes to acting e.g. grounding D15's activities it is a different matter - that needs solid justification and agreement - D15 needs respect and her rights can't be trampled on.