...
I guess I'll wrap up with some thoughts about validation. On these boards you'll find tips about validating feelings, not lies. That's good advice. But in practice, I've found that talking endlessly about negative feelings and purported slights/abuse/grievances is counter-productive. You see, the pwBPD doesn't seek context, perspective, understanding or closure. She's not looking for resolution, or to move on. My opinion is that the more she rehashes the negative feelings and accusations out loud, the worse she gets. I think if you "validate" her too much, what's happening is that you're essentially rewarding her negative thinking patterns with attention, and she's incentivized to continue! So in my experience, I think that a time out might work better. I guess that's why the recommended treatment for BPD isn't talk therapy (i.e. to explore thoughts and feelings for greater understanding and self-knowledge), but DBT.
I don't think you should look at validation as an end in an of itself; it's a technique to prevent conversations from blowing up into larger fights or blame games. But you still have to find a way to end the conversation.
All this is easier said than done, I know, but maybe you can try using their own language against them. The "I don't feel" and "You don't seem to be" etc. kind of statements.
I've also considered that validation might be the first step, but then repeating & rephrasing their attacks and unhinged statements back at them can take some of the wind out of their sails, and force them to retract things or otherwise calm down to try to parse out what's happening.
"
I'm sorry, I understand you're upset, but you think because I looked at my phone, I'm intentionally ignoring you?"
"
When you said XYZ, it sounds like you feel bla bla bla. I'm just trying to understand where you're coming from here."
I tried this sort of thing; I also tried the "leave the room to defuse the fight, but do it kindly," technique, which is really hard to do when someone is screaming at you for no reason, or insulting you. I'd find that sometimes validating and repeating that I loved her and she didn't need to worry or feel anxious about it would temporarily defuse things. Sometimes (I can count the number on one hand), it would be the last I'd hear about that one concern. More often (I do not have enough hands to count the number) the next day, or a few days later, I'd hear "
I was thinking about our discussion from yesterday/last week, and I still think that bla bla bla..." and the hair on the back of my neck would stand up as I knew she was going to keep hacking away at this until she was able to provoke a fight - over it or whatever other perceived slight she could come up with in the moment.
but yeah, there's always those doubts, especially with the way people with BPD just move on like nothing happened and 'seem' happy. It makes you think, 'damn, was I really that bad and crazy? they were right and are doing way better while I'm here crushed'. 
