I’m an outsider. I don’t know if I can tell you these things without insulting you in your own country.

Maybe you could start off with "Sometimes, I meet the occasional person who doesn't accept me but most of the people I have met have been really lovely."

This way, if the other person wants to know, they can ask you to elaborate. You have kept the conversation about individuals--not whole countries--but that opens the door to discussing the racism you really do experience.