This looks rather like what is called in the sort of circles that use that sort of language "female relational bullying". Using methods that are supposed to protect people from attack to attack them - we had little girls who used the anti-bullying mediation process to report their victims as being the bullies, while giggling and sneering at the victims. (Without noticing a teacher observing them.) Giving the impression of being an ingroup that is excluding the victim - hence references to supportive friends, and special language forms. This works in schools where victims may be wanting to be part of the group, but is not very effective in adults. Projecting their own behaviour on to the victim. It's rather sad when it goes on into adulthood.
An elderly friend of my sister told me that these girls spend all their time planning what nastiness to do next.
While the writers of educational texts have many suggestions of methods to deal with boys bullying, there was scant advice in my day of how to deal with the girls.
Penny