Ethel is right in one sense, but can I just be the first to say that there's really nothing in your story to give us any impression that he's playing away. I work away from home too from time to time, and my marriage is secure, loving and trusting enough to deal with that. I think you need to have a long hard think about whether you are secure enough as a person to hold down a relationship. Your insecurities are rooted in his past fling with you, and that's really understandable, but he chose to be with you.
That said, I really am worried that you're afraid of him - are you physically afraid or are you just nervous in case you cause a row over nothing? If it's that you're afraid for your safety get out of there tonight.
I do wish you well in whatever course of action you take.