When i was in high school, if someone had to go to hospital and had cracked ribs, that story would have spread around the school really fast. Especially in a school where there is obvious rumour mills at work. And if she really cared about MC, she would have tried to pay attention to any "news" regarding him in school, even during the separation. So yes, she might still care somewhat about him, but until she really proves otherwise, it's obvious that she cares members of the bitch squad way more and is willing to take their side over his, considering the offer she gave to MC was to prove that her friends weren't that bad and MC just perceives them as evil bitches.
So while i accept that there can be redemption story for the members of bitch squad, they will have to do serious work to gain it, including public admission of their wrong doings and apology. No way would i personally accept any private apology, since that could very well be just their way of burying the whole bullying issue under the rug.