you dont control your whole brain. if you dont tell him and get away with it, you will teach yourself that this crime goes unpunished and your instincts will keep shooting armor piercing rockets once again when you are confronted with a similar situation that would lead up to a similar act.
also telling him would be doing him a favor. or not. totally depends on the person. but it is his right to know, and "rights" are the most important things to a human.
Seriously, I'm in a long distance relationship myself and I would never do that. You have shown us that you need the touch of a man to get by. You're supposed to be a college student, where is the reinventing yourself and independence that you're supposed to go through? I'm all about keeping your relationship, but seriously girl.
I don't have much to say about the relationship issues, but on this note:
"I think what you need to do is think about why you did, honestly and seriously with yourself and what you want from your life."
...I would like to point out that you are looking to be dramatic here. Take note of this, in your OP:
"in polite company...b-but having him so far away"
Why the "stutter"? I can accept the overly poetic and dramatic descriptions as an understandable outpouring of emotion, but we don't naturally stutter on computer monitors. It's not like your fingers tripped, hit the hyphen key, and then hit the b again. You purposely and deliberately put that there, as though you're acting for us, putting on a show.
I'm not asking you to defend yourself to me and frankly I don't care why you did it or whether or not you're looking for drama, but I want you to think about it. Maybe it has something to do with why you cheated in the first place.
Ok, based on what I saw most everyone else say, I'm going to say something different that might seem bad to some people.
I think what you need to do is think about why you did, honestly and seriously with yourself and what you want from your life. Do you want to continue this relationship now or take a break and start it up again. If so, telling him the truth, will kill most chances of that. The damage to trust will never be repaired and it never get better. Even he stays after you tell him the truth, it will create this festering wound that will never get better, just sit under the surface of everything and rot slowly with time, getting worse.
In the end only you will know what you did, it's just a matter of how much you can life with your own guilt. Can you put it behind you and move forward, or will it eat you up inside? You have no reason to tell him, unless the guilt will destroy you. Then you have to, and as soon as possible, because that is the only way the truth route will have a chance to succeed.
For reference, I've been where you were. I finally told them, and they stuck around for another 2 years, but they never forgave me, never let it go, it was always there eating away at everything. Even when she left 2 years later, she blamed it on something that happened 2 years before. My friend who is married is going through the same. And he has never let go of it, resents her every day, and calls her a horrible person all the time, and only stays with her because of his religion.
It'll kill your relationship if you tell him. But also, if you can't live with your own guilt, that will kill your relationship too because then instead you'll rot from the inside out and be unable to confide in them. I've been there too, unable to say what I was thinking or feeling, feeling like everyday was a lie. Eventually that falls too.
Neither choice is really good. The best is just to try to start over somewhere else. But if you are planning on staying I would recommend forgetting that it happened and trying to be a better person in the future.