This is a VERY DIFFICULT road....the best thing to do when the triggers are hit and the fighting starts, when she starts to devalue, DISENGAGE!! She cannot fight with anyone if there's no one there to fight with. Hand her a mirror, tell her to drop the smoking gun, and have a long talk with the reflection in this shiny little window thing, while you LEAVE THE ROOM (this can be INCREDIBLY difficult to train yourself to do, and will probably make her very angry the first few times she's handed the mirror, but...) and go find a place to sit down and decompress. She will come to you when she's cooled off, even if it takes a few days. Always know she'll cool off. Went through 2 years of this recently, and if I'd only known what BPD was, I could have likely saved the relationship BEFORE it was lost. At least we've salvaged a friendship out of it, and I'm trying to help him find himself as best I can. This is NOT an easy one....staying with someone who devalues you on a daily basis, is crushing; even to the most hardened hearts.