What can I do for my 12 year old daughter regarding toxic friendships?

[AmazingBouncingFerret]

My DD turned 12 last year and is still trying to navigate year seven.
She has an entirely new friendship group that is very mean girls in my opinion, since making friends with this group she has stopped being a librarian and has given up on all her after school clubs and was declaring subjects as boring even though three weeks before she was loving them.
I’ve just been receiving messages from her at school saying some of the girls are spreading lies about her such as she slapped one of the other girls, now a friend of the girl she allegedly slapped is threatening to beat her up.
I have spoken with the school already and given the school all the names of the girls involved so hopefully they can deal with that side of it but what can I do in the meantime?
I want to get across the message of walking away from this particular group and starting afresh. I’ve tried to tell her that all the threats of violence and aggression is not friendship but her self esteem is way down and her anxiety is through the roof.
I thought maybe some books I could download to her fire tablet? Something about raising self esteem in teen girls maybe? How to find strength to walk away from toxic friendships? Does anyone have any advice or recommendations?

Bumping this. Probably shouldn’t have put it in chat!

All you can do is to keep coaching her, keep talking to the school, and provide her opportunities to make friends away from school.

The problem she will face in walking away is that it may be hard to make other friends. I wonder if the teacher has advice about this? Could moving class be an option?

Stupidly, it never occurred to me to ask about moving class. I think if it carries on it certainly is an option I could put out there.

I remember reading this book when mine were young
Best Friends Worst Enemies it covers girls and boys friendships and I found it quite useful (It is more for you than your DD to read) If you put 'Girls friendships book' into google there seem to be a variety of fiction and non fiction books that would be age appropriate for her.
With mine I found role play quite useful - create scenarios where she can practice what to say in certain circumstances, and then it becomes easier when the circumstances arise (I'd keep it very casual and part of everyday conversation because at 12 she may well find the whole idea of role play a bit cringy )
Other than that I would try to get the school fully on board. It will be a big step for her to leave her friendship group and find a different one - and there may well be a lonely period while she finds her feet - that will be daunting for a 12 yr old. School can help by putting her in groups with different children, getting her to do tasks with different children other than the ' mean girls'.
Are they any girls she quite likes that aren't currently close friends that you could ask over at the weekend, to go to a film or have a sleepover. Are there school clubs she could join where she could meet some different children?

i thin it is just a case of talking through with her how to stand her ground when she i in a situation where she is uncomfortable, how to stick to her opinions he likes and dislikes and not let other force her to drop things she enjoys. Practicing how to distance herself from bad behaviour. Talking about how good friends treat each other, and helping set up opportunities for her to meet a new group of children to befriend.
Good luck - the social side of school can be such a minefield for youngsters.