TL;DR: another parent has messaged me to say that my son and his friends were being mean to their son. I've spoken to my son and he has a different view, which is that there was some banter between all of them that they all joined in with and where no-one was singled out, and then that this boy walked off and stopped speaking to them, with no warning signs that he'd stopped enjoying the banter. I've also spoken to the parent of one of the other boys, who's story is consistent with the additional fact that the 'victim' was hitting the rest of them, which my son has also now confirmed. I've talked to my son about empathy and inclusiveness, but not sure how to respond to the initial parent or whether to even respond at all, given that there are two sides to the story.
Longer version: this happened during a lunchtime party for my birthday celebrations. The boy in question was with his Dad - who has said nothing about the whole thing - the message came from the Mum, after Dad and son had arrived home but when some of us were still at the party (she hadn't attended the party because she was ill). In other words, she knew that the party was still going on when she sent the message. To me, this indicated a seriousness about the situation that needed immediate attention. But when I looked into it, the banter seemed to amount to being asked to fetch the ketchup. The boy is younger than my son and the other boys. This younger boy has always looked up to my son, but in recent years my son has started to find him a bit annoying and doesn't really enjoy spending time with him anymore, which I think is understandable as kids grow older and chose their own friends. My partner and the Dad are good friends, and so I am friends with the Mum as a result. I find the Mum quite difficult to be friends with, as I find her prone to unnecessary drama and manipulation (although no doubt she doesn't see it that way) but I do my best to make an effort for the sake of the friendship between the Dads. The other two boys at the party are the same age as my son, and also one of them is my son's best friend. Her message said that her son had arrived home in tears due to my son and the others teasing and being mean, and she said that he's struggling and having a hard time right now so doesn't need this. I do feel sorry that her son is struggling in life, but I feel that's a matter for his parents to deal with and not be made to be my concern, or at least not there and then. I don't see why she had to message me during the party, which was meant to be a nice chilled out day but her message effectively spoilt it for me. She's immediately jumped to her son's defence over something that turned out to be not all that serious in the end - and in fact the person doing the most disturbing thing was her own son as he was hitting the others. I can understand that he might have felt left out given that he's younger than the others, that he might not have known how to communicate that he wasn't enjoying the banter, and perhaps also jealous that my son's best friend was there, which could have been unsettling for him as came to realise that he wasn't going to get my son's full attention.
So I'm annoyed with her creating a drama (which is not unusual for her) and that this time she's brought my son's best friend into it. I also happen to be good friends with my son's best friend's Mum, which I suspect she is also jealous of (due to a previous drama last year which I won't go into). So I'm trying to deal with it rationally whilst at the same time feeling very frustrated that children have been brought into a drama that's essentially fuelled by the green eyed monster rather than sensitive parenting.
However, I'm very conscious that she's as good as accused my son and his friends of bullying, which I feel should be taken very seriously. So I want it to be a learning opportunity for my own son, but just not sure how to handle things with her. I hope this all makes sense, and really appreciate some different perspectives to help me figure out how to respond. Thank you!