Relax. Just reply to them : Hola, que pasa maricones?
https://en.oxforddictionaries.com/definition/racismWhat the OP describes is not racist. It's a lot of bad things, but it's not racist. Of course, they could be calling you "pinche gringo" in spanish, but still, talking in their own language it's not racist per se.
...I am paranoid they are always bitching behind people's backs (hence not speaking English)