D17 confronts uBPD mom

[40days_in_desert]

A little back story:
My two oldest daughters (14, 17) live with me full time. D14 recently moved in and D17 has lived with me for 2.5 years. D17's relationship with her uBPD mom (40days ex) has been strained for a very long time... .say 5-6 years. One of the most significant events that caused their relationship to plummet was an incident over 4 years ago. 
In the summer of 2014, my ex took our five children to visit her aunt and uncle for a week. While there, D17 (then D13) woke up around 2am and decided to look for her mother for some reason. Her uBPD mom usually stays up most of the night and then sleeps in until late morning. She heard noises coming out of a room where uBPD mom's cousin was staying. Long story short, D17 heard what were sounds of her mother and mother's cousin having sex. She listened for 15 minutes. No denying what was happening in that room. She asked her mom later the next day what happened in that room. Her mother (again, this is my ex) told her that she was consoling her cousin because of what he was going through in his marriage. Her mother told her this in an angry, shaming manner. D17 had brought this up once since that night but had a similar response with similar yet different details.
That brings me to the present. At least this past week. I was out of town for work and D17/D14 went to their mother's for dinner. D17's mother brought up something that I had done in the past and how it affected her (uBPD mom/ex) mental state. This is pretty typical of uBPD mom to blame me. D17 has learned to not engage and ask me later to get the truth if she feels the need to do so. This time, D17 told her mom that she has a hard time believing her because she seems to always make herself to be the victim and doesn't bring up things that she herself was guilty of. uBPD mom asks, "Like what?". D17 responded, "Like the time where you and (1st cousin) were having sex when we were visiting (aunt and uncle). Her mother tried denying it once again but D17 said in a calm yet assertive manner, "I was there for 15 minutes listening. I know what I heard and I won't let you change that.". Her mother was quiet for about a half minute then explained what "happened". Her explanation is that her cousin took advantage of her because she was in a vulnerable state. That all they were doing was "dry humping".
After D17 shared this conversation with me, I asked her two questions. 1) What do you think about your mother's explanation? and 2) What did you take away from that conversation? D17 stated that she didn't believe her mother. That it's hard to believe anything that she says. The most important take away was that her mother never once mentioned or acknowledged how that whole incident affected D17, never apologized and only seemed interested in defending herself by blaming someone else.
D17 has finally agreed to pick out a therapist to talk to.

[worriedStepmom]

Good for D17!  You must be really proud of her for being able to calmly state her truth to her mother and to see through the web of lies and victimhood her mom tries to spin.   

I'm so glad she's agreed to see a therapist.  I hope that it helps her continue to process everything she's been through.  Her mom sounds like a real piece of work.

[Turkish]

Is amazing the lack of empathy towards others which people will go through even when obviates caught in a lie.  Not to defend your exW, but it wasn't like she was going to admit to being caught in a shameful act.  For the most part,  it's easy not to lie: don't do what you shouldn't be doing. 

You handled it well. That's a gag-worthy subject to discuss 

[40days_in_desert]

Thank you Turkish. You're right - it is gag-worthy. Unfortunately, my ex's sister recently confirmed that this wasn't the first time between my ex and her cousin. It has happened a couple of years before we met.

[Harri]

Wow.  I am impressed with your daughter's clarity of mind on this.  For speaking up too but that she did not let her mom change what she knew and trusted herself?  Wonderful!

[40days_in_desert]

Harri - I can't express how proud that I am of D17 and relieved that she hasn't exhibited her mom's BPD traits so far. Now that D14 decided to move in with me about 4 months ago, hopefully I will be able to post a similar victory of her's a few years from now!