hi lynn i think you handled this very well! often times it helps to alert the school rather than privately approaching another parent. it sounds like the school also did a great job so i hope this helps you to know this from us. clearly your daughter is on spot of what to do. you have educated her well.
as for the other child, it could be innocent at that age but erring on the side of caution was definitely the way to go.

just read your updates...no need to try to make peace with this family as you know already now. good to separate the children as much as possible. the less said out loud at home the better-little pitchers have big ears-your daughter can put this behind her faster if she doesn't hear it rehearsed, imho and from experience. it gets very confusing for children to deal long term with things like this.
hopefully she can just get along with being a little girl now.