Hi butterfly,
Welcome

. So sorry that your wedding fell apart and you broke up during the engagement.
Is your pwBPD willing to give things another try? Do you still speak or are you in contact?
Times of transition can be extremely triggering to a pwBPD. They have a strong need for control and all of the unsteadiness of a move and a marriage could cause them to feel quite a bit out of control.
As for other family members, remember that they are often brought into a drama triangle with your pwBPD. They may have a tendency to try to rescue too. Today she may be the rescuer and tomorrow she may be the villain. I would suggest just removing her from the equation. What she thinks or says has no bearing on your relationship.