So I know I'm wrong

Ok I know I'm wrong but the guy that I'm with knows I'm not happy and haven't been for the past few months. Yesterday one of my friends of almost 10 years told me he wanted to hook up with me. I have always liked and wanted a chance to be with him. Well last night me and my boyfriend were having sex I imagined that it was my guy friend. I don't know what to do. I don't want to be with him. I hate hurting people. But I'd have to relocate to Nebraska from Florida to be with him. Also we have already decided that I'm going to visit him in July. I know I'm wrong to be thinking while we are having sex to be thinking about my friend. Advice on how to handle this please.