TL;DR - how do I talk to my kids about their step-mom (has BPD) kicking us out with no notice, no goodbye?

To make a long story short, my partner of over three years, with whom my daughters (6 and 10) lived with for over two of them, was diagnosed with BPD a few years ago. She didn't take it seriously and I didn't know enough at the time to do so either. You know how these things go, it trickles out here and there, but at first it's seldom enough to excuse the abuse, because they're very sorry and here's a two week love bomb.

Well, we broke up about a month ago, at which point she gave me a soft deadline of June to move out. Understand, I JUST got hired into a new job, my first since completing my degree. This isn't a good time to move. Things were really peaceful at first, but after a disagreement, which felt very gentle at first, erupted into her kicking me out. At first it was for the night, then it was for the weekend, by that night she requested that I do not come back except to pack and move, which I must do by the 1st. Now, I don't know if that's legal, but honestly, I can't go back there to be around her anyway. I need big boundaries and I know.

This happened with my daughters at school. They still don't know why we're staying with my parents. She told me that she does not want to have a relationship with my daughters going forward. I'm both relieved and broken hearted. I know her affection to be dangerous, but she has been an incredible step mom to those girls, if at times a little hot and cold. They never caught the wrath and for that I am thankful. This could be devastating for my daughters. They are losing one of the strongest relationships in their lives as well as their absolute favorite dog (hers).

How do you talk to kids about these big, rash decisions made by a loved one with BPD? They have no idea she's dealing with this. Truth told, I'm angry and don't feel safe, but I love her for the effect she's had on my girls. And myself! The one part of her is wonderful, but the other part is driving.

Please any advice would help.