Confusion and Decision Making

Talked to mom today. I've decided that I can't go through with it. I can't get married. Maybe there is nothing real between my best friend and I. But there is surely not enough between my fiance and I... otherwise I wouldn't be so unfaithful, right? I can't marry someone I'm not in love with. I don't know how I'm going to deal with it or how I'm going to tell him, but I am going to call it off. I'm scared of what comes next.