I don't think there's anything wrong with being a whore, i.e. getting paid for doing sexual things, so every time it's used as an insult, I am at least temporarily confused. That it's used as an insult in this book just breaks my brain even more.

Anita really does have no loyalty to anyone at all. All these people she supposedly loves, she treats like garbage. Unfortunately, I can't think of an appropriate specific insult for that.