It is way too much drama over someone who you weren't really a couple with (according to you and looking into his lack of interest all these months). This is way too much stress.

You have been posting about your active pursuit of this guy and his resistance for a long time and I am glad you stopped. You need to respect yourself imho.

Completely block him everywhere and stop contacting him. How and what rumors is he spreading? What are the rumors about? Your communication with the guy was so limited and usually initiated by you so I dont see what the rumors coulld be about? I would take it up with your son why is he engaging in rumor spreading? What kind of relationship you have with your son???

Unfortunately you can't control what people do, just distance yourself from drama.