Hi wanderlust6294,

I'm sorry to hear that. It's frustrating, confusing and painful when you're with someone and they leave and do irrational things. It's hard.
I'm glad that you have found us. Many members here share similar experiences and can offer guidance and support. A pwBPD want intimacy and fear intimacy at the same time and at times feel engulfed and push those they love the most far away. She sees the world in black and white and the people in it as all good or all bad. I'm not quite sure why the introduction of your kids triggered her? It may of been the significance that you were committed?
It's confusing when your partner leaves you for someone that may be very different than you and she's idealizing this person and devaluating you. I can relate.
Here's some info on splitting and idealization / devaluation:
From idealization to devaluationTopic: BPD BEHAVIORS: SplittingHang in there.
--Mutt