Sticky situation...help?

I have recently had some stuff happen in my life that has made me a little wary of being alone with guys that aren't my dad or boyfriend (who is currently states away). Today I had a guy friend that just came back in town ask me to hang out. I would like to see him but he asked me to come over to his place. I made an excuse for now but if he continues to ask why I'm blowing him off, how do I tell him that I'm uncomfortable with the situation without offending him or having to tell him about the event that happened that led to me feeling this way? Advice?