I need help! STD??

Okay so long story short. I had unprotected sex with this guy I had been talking to for a while and we recently stopped talking. Like we still talk as friends but we never became anything more. Well I also recently got tested and I came out positive for chlamydia.   It's a non life threatening std, thank god. I need help!! How do I tell this guy that I might have given him an std without him getting mad or think bad of me.