Many thanks for your reply.

The children have other grandparents who are wonderful. We even had to move in with them short term while we had building work carried out on our home and it was lovely so I guess they aren't missing out from that perspective.

The in-laws have done this before, years ago. Similar thing, texting then leaving the family group chat. It's very school yard behaviour. Once they didn't speak to us for years. Again, all said in a text before vanishing.

Now this is the last time. Our children deserve better. I just want to say something that is concrete and clear that we don't want them around anymore