SDT I doubt they will want to apologise, sadly, because they wouldn't want people knowing how vicious they were and they probably did not see they did wrong. Apologising to you would be an admission and they aren't prepared to do that.
I had dinner with a girl from school a few months ago. She was part of a gang of 3 who would regularly put me down (not bully as such but would always say I wasn't fashionable/skinny/pretty enough etc, but next minute being all nice to me). I was surprised to hear from her and tbh I delayed responses because I was unsure of her motives, although the curiousity was there. When I did respond, I was honest and said I did not know why she wanted to meet with me, as she pretty much emotionally damaged me at school (at one point she got her parents to go to the school about me because once I retaliated back to her, only once mind but god there was not half a kerfuffle over it and sadly I wasn't believed). She did not answer directly but insisted we must meet up. So we did. I will admit to feeling slightly better that whilst I am way slimmer than I was at school, she on the other hand (having the figure of a matchstick at school which I always envied), she had ballooned to twice the size of me
Petty I know to feel that way but I did. I confronted her over the the things that were said and she basically said that I was just as bad so I should apologise too!! I looked at her and realised that she was never going to take account for her actions and because I really did not want huge row (which I could feel bubbling), the coward in me changed subject and we talked about every day life and left. She has suggested meet ups many time since but I have not responded. I still now do not know why she wanted to meet.
As some of the posters have said, hidden bullies are the worst and she was one of them. Because she was in the "popular" gang at school who all the teachers liked, it was impossible that she would be anything other than nice. Me, on the other hand, a quiet wimpy non confrontational child was of course responsible for causing her upset because just once I dared to stand up to her.
I agree that certain things do not mean "bullying" as such. I work at a school like some of you and indeed every day see parents saying their little darlings are being bullied, when I see it is the other way round. That is why sometimes I agree schools should have CCTV!
It is such a tricky sensitive subject; some schools and teachers do not do enough, neither do some the parents of bullies. From the inside I can see that some parents refuse to acknowledge their child has done anything wrong, even if proved, which basically leaves the school hands tied, short of expulsion or suspension but to me, that child will go on perhaps to do it in another school. I like to think if DD was ever to be a bully (god forbid) I like to think I would take as much action as possible. Nobody wants to hear their child acts this way, but we are doing our kids far more justice by pulling them up on their behaviour, rather than blaming others or simply brushing it under carpet.
Every situation is different and we as parents, do the best we can for our DC.