I was in quite a similar situation once I told her that she was really toxic and it didn't go well. DO NOT TELL A TOXIC PERSON THEY ARE TOXIC it is best they find out on their own bc if you tell them they will immediately try to guilt trip you into thinking you are wrong. Instead try and give them subtle hints into realizing they are toxic and slowly distancing yourself from them.
Examples are talking to your other friends more, not sitting too close at lunch, and try and sit near your nicer friends.