More of a WWYD rather than an AIBU.
DD12 had a good friend, let's call her Lila, all through primary school. Lila and DD went to different secondary schools. Lila's dad was unfortunately diagnosed with a serious illness about 6 months ago. DD did her best to support Lila, she came to our house a lot for sleepovers etc and all was good between them up until this summer. Lila went very distant over texts, not replying and making up increasingly outlandish reasons for why she couldn't meet up with DD. Eventually Lila turned on DD, sending her a barrage of texts saying she was annoying, why didn't she fuck off and let their friendship go etc. DD was absolutely devastated and it really rocked her confidence, especially as she is still finding her feet in a new friendship group at her school.
I see Lila's mum a fair amount as Lila and my older child do the same sport.
Fast forward to today, Lila has unblocked my DD to ask her for her brother's number as she likes one of his friends. DD said no and Lila sent her a meme calling her a f*#ing r!#ard. I have seen screenshots of the whole exchange.
Would you say something to Lila's parents? I bumped into her mum today and she was really keen to start a conversation, but I just made my excuses and left quickly. I don't think she knows how Lila has acted towards my DD, but obviously this is an awful time for their family, so I don't want to add to that.