how to decide what is right and what is wrong_2

My affair with my old school friend has reached another level.After spending a considerable amount of time on the phone and meeting occasionally for lunch at the nearby restaurants,he wanted a small kiss. I was hesitant as I knew that one thing will lead to another and I was not ready for it. But he promised that it would be a kiss and he would stop then and there. OK,I'll do it just for him.But the actual thing came as a bolt. I was very satisfied with my sex life with my husband.But the kiss just came as a hurricane and blew away the myth. It was as if I had never been kissed before.I could not tell him the truth but somehow he knew it.He being a perfect gentleman,kept his promise and withdrew after one kiss.I wanted him but I never had the guts to tell him the truth.I still can not decide what is right and what is wrong.