I cheated BIG TIME. should i confess?... help?

go to college in stony brook and my boyfriend goes to columbia its a pretty big distance and it kills me that i dont get to see my boyfriend when i want to usually it is only on the weekends . and aometimes every other weekend ....we still talk everyday on the phone and he calls to say good night. iam very upset i feel like telling him i slept with one my room mates friend but it happened so fast. the sad part is that my boyfirend wasnt even on my mind i actually have a good conection with mike we are always laughing i dont even laugh as hard with my current boyfriend mike is v ery sweet he is the complete opposite of my boyfirend in everything. maybe i lack intamcy with my boyfried thats y i cheated or maybe i feel like i dont get enough emotional response like him being there for me when i need him but the thing that kils me is that me and my boyfriend are always talking about marriage and he says he sees a future with me when we finish school ....ahh but sometime my boyfirend acts ike he is cheating on me lke he dosent pick up when i call or respond to my emails but he still says he will never cheat on me..:( NEWAYS IVE DONE IT TWICE WITH MIKE AND IAM NOT SURE WHAT TO DO ! i want to tell him but i dont know if iam making the right decision my boyfriend is a nice guy he had bought me alot of stuff and taken me to many places when we use to live together but things changed little by little also!!!! mike wants to see me tomorrow and ia dont know what to do i feel like seing him cause he gives me the emotional care like he is soooo sweet and charming (something i dont see from my boyfriend) and mike want to take me to go eat some where fancy with him so he wants me to be all dolled up but!!!!! i know i love my boyfriend we have been together for 4 years and he will always be my first love we lost to each other and i would flip out if i find out he is sleeping around with sum roomate of his and also he wants to go to the airforce so its not like iam going to see him even if we do get married iam going to be like a military wife and i think they all cheat at s ome point....i would love to marry him because he is smart and he will make a geat dad also i know stability would be fine with him maybe mike is a test from the universe do you think ill get caught?? does karma exist?? help ... please any advice would be great should i tell him and if yes how should i tell him????