The ex-friend is a grossly insecure person, which I think is governing her behavior, and, there was one really strange thing about her, is that she really takes pride in the fact that anyone she works or worked with (save her immediate boss) hated her.
Hmm, I knew someone kind of like that, only they bragged about have to bring a complaint or lawsuit against everyone they'd worked with. It didn't exactly endear this person to others.