Feeling very much for you both!
In my Daughter's final year of schooling and during study leave, her (former) best friend messaged her to ask what she was doing while ''her'' newest school buddy put up on snap chat photos of the rest of the year group at her place, supposedly studying but clearly having a good time.
We live in the same road as this piece of work so it was no problem for DD to go had she been invited! I spoke to X BF's mother who assured me DD had been asked to come along... so yes they are prepared to lie.
Three years and different universities later, the X BF and her cling-on from the final year of schooling are no longer friends. I have blocked the one across the road from reading my FB posts (as DD had already done earlier in the piece) as she would always post the ''angry face'' at anything I wrote...
I have no idea what her intention was, apart from breaking up a friendship. I just put it down to a very immature and spiteful Girl and now a young woman who is not happy with her lot in life.
Keep supporting your Daughter, take her out and get pedicures done, go to the pictures together, take a drive, try a new place for lunch, walk your dog (if you have one) in a new place. She is going through a terrible time with these people and if you can balance other parts of her life with good, then it gives perspective and help for her not to dwell on the negative and spiteful actions of the few.