Hi Flannery,
I'd like to welcome you to bpdfamily, I'm sorry hear that, your D17 was just recently diagnosed with a severe mental illness, that has to be difficult for her to absorb and you're family too. I ambassadors glad to hear that you're doing all the right things to help her.
A pwBPD have all or nothing thinking, it's a feature of the disorder, they can't see people as integrated whole, bad people have good qualities or good people have bad qualities, you're either all good or all bad, from the sounds of it she's splitting. Also, feelings equals facts to a pwBPD whereas it's the other way around for us, feelings are followed by facts.
What did she get mad about?