Since our kids were very young, with ANY playdate... we PUT AWAY any toys or belongings, that we do not want touched or broken or whatever.
And we explain to our kids.
Our kids will even tell their friends "that is off limits.... its special... " etc. AND my kids, will tell me... IF something is going on. That a toy... is on the verge of being, broken or the child is rougher etc.
Yes, we taught our kids, HOW to say things like that.
And at times, we even close the doors to private rooms... and my kids KNOW.. that other company is not allowed in those rooms. And that we put things we don't want touched, in that room. And my kids will tell their guests... "that room is off limits... its private..." etc.
And since my kids and their friends can read... I even sometimes, when I have a TON of kids over... will actually put a sign on the door... "Please do not enter. Private."
Beyond that.... my kids when their friends are over, have a ton of fun.
They play. I let them.
Its fine.
Broken toys, are not the usual that happens.
For now, just suck it up.
DID the child's parents, SEE their child, break the toy?
What did they say???
If that were me, I would have apologized, and offered to replace it, out of etiquette and just being, fair.