I'm really sorry to hear that your daughter's friend seems to be behaving in an emotionally abusive way. But it's amazing that you've raised her to realize that she doesn't need to tolerate poor treatment. You should be proud!

In case it helps, I've written pieces before about toxic friendships. There's this link and then, at the link, another one. No pressure to read, just sharing in case you (or she!) find it helpful:

https://psiloveyou.xyz/8-simple-steps-for-a-drama-free-friend-breakup-937c1b577708