I doubt he enlisted people to spy on you. I think because you like the same crowds it’s inevitable you’d run into these people or into each other.
This particular occurrence just proves what a low class people they are. Who asks a recently divorced ex of your friend what’s her dating status. In fact who asks anyone of their dating status? So tactless. Who does that. That’s just not a thing to ask anyone whatsoever
I just had this conversation with my aunt about some people asking tactless dumb questions with no reason. So pointless. Just bad taste and lack of finesse. Next time ask back “why are you asking?”