Ours is like that too, coddy. Everyone always makes a big effort to include parents of children who started after the rest of them, it couldn't be less cliquey to be honest. We do talk about the children a bit, but more in terms of sharing concerns than hilarious anecdotes, and there's a complete mixture of single parents, married mothers and dads, SAHM and working parents.
I'd talk to you too Fio, I'm really sorry you've been caught up in something like this