I would love to post something meaningful and insightful that would make it all go away and make you feel better Faelar. But unfortunately I can't.
I have been cheated on before, but that was different because we were already in a relationship... I don't even know how to start in putting myself in your shoes. My first instinct wants to make some joke about this situation, just to make you laugh or whatever. But I doubt that would help and I can't come up with anything that wouldn't be hurtful to people you obviously still care for.
The only thing I can suggest is don't become like me. I've bottled everything up my entire life and never cared for my own feelings. I can't forgive people (even for stupid ***), and it has made me a spiteful and cruel person. What I'm trying to say is, try and let thing go. Share how you feel about the situation, don't close yourself off.