Sounds to me as if she is learning how to navigate things well, Mare. You are doing an excellent job as a mom.
Great update, Mare.
I dealt with and saw a lot of situations like your dd's working with kids, coaching that very age group, plus my dd's years. One thing I was going to mention earlier is that there's hope - what I often witnessed was the "nice" kids being forgiving to kids who went to the dark side for a while. After all, they're nice.
It's likely that your dd did participate in picking on other kids. Even if she was just a follower, she didn't stay in that group for as long as she did by not going along with it. It shows that it's not really her style, though, that she did speak up and while it's likely very painful right now for her, she'll be better for it in the long run. Good for her! :nansel