<human>: Me (female) and my best friend/co-worker (male) are both in our early 30's- met at work

I have fallen hard for him. He seems to like/care about me too. We have been best friends for over a year now. We work for the same company, just in different offices in different states. I have only seen him twice in 6 months but we talk daily (I've used 4000 minutes this month just talking to him)

He has sex with other girls while I am at home not doing anything because my heart is invested in him. He does tell me about meeting girls and taking them home even when I have asked him to stop. I get mad, he says he is sorry, and that he won't do it again. But yet, he does it again. I can see where this is going and I know it isn't going to turn out like I want it to. 

He obviously is never going to choose me. He says he is scared to even have sex with me because I am here and he is there and what happens if we do hookup and end up wanting more but distance keeps us apart?

Here is my problem...how do I move on when I have to deal with him on a daily basis for work? I love him and want to tell him, but I can't get up the courage to say those 3 words. And not to mention when he gets mad at work he tends to take it out on me when I am only trying to help resolve his issues. Any advice/honesty would be greatly appreciated.

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<bot>: Crazy about my best friend and co-worker, and he knows that. How do I move on or should I hold out hope for more? Should I distance myself from him?