Danny, sorry to hear this, but unfortunately it happens. I wouldn't worry too much.
about 12 years ago I had the customer from hell, probably this guys cousin. anyhow he was in LA and when I did my exhibit at the NAMM show he started papering the show with posters with my picture defaming me. it was hilarious, he barely made it out of there in one piece, he was lucky the cops escorted him because there were several people ready to take him out. it all happened so fast I never got to see him, though I had a few lawyers come to the booth offering to prosecute him for free! bottom line everyone knows you're a good guy and he'll only make himself look like a jerk.
best,
lou