Hi Heartbroken Daughter,
Invalidating and frustrating, huh?
In my experience, most people caught in the triangle just want to get out and not "choose sides." With all the information that I sent to people who were brought into my uBPD mother's attack on me, each of them would just delete the email I sent without reading it fully. Only when a psychiatrist diagnosed her as having Delusional Disorder (I honestly believe incorrectly) did anyone pay any attention to those symptoms.
After several years of witnessing her behavior in my absence did they finally come to some of the same conclusions I did. Still, the only ones who truly KNOW her full range of behaviors are my siblings and I. I had to learn to let go of what others thought of me, and it was very difficult to do.
These are all from reputable sites, and essentially they all say the same things. He may find WebMD and MayoClinic recognizable, but those don't go into much detail. Any Google search of Borderline Personality Disorder will give you essentially the same thing, so you might even suggest he do that on his own or cut & paste the list of symptoms within the email you send with a link to the source. That way, he can just read short bullet points without having to go further until he is ready to do so on his own.
I wish you the best of luck!
www.psychcentral.com/lib/symptoms-of-borderline-personality-disorder/0001063www.mayoclinic.com/health/borderline-personality-disorder/DS00442/DSECTION=symptomswww.webmd.com/mental-health/tc/borderline-personality-disorder-topic-overviewwww.en.wikipedia.org/wiki/Borderline_personality_disorder