I'm not a good man, I'm not a good person. A good person wouldn't cheat on someone who has stuck by me through all of my shit.
Do not define yourself, whether or not you're a good person, by a single act.
We all make mistakes.
If you've made a mistake then take responsibility for it and clean up the mess you made.
But don't sink yourself into a deeper hole by piling on to the reasons you are worthless, or not a good person.
You know who you are, you know the good things you think, the good things you do, the loving and the kindness that are a part of you. Making a mistake does not undo all that.
He doesn't deserve that, and he doesn't deserve to be stuck with someone like me. He deserves better than that.
Stop it. You are beating yourself into a hole that's not going to help anyone or anything.
You're right that your bf does not deserve to have his trust betrayed. You behaved badly, you made a choice that was careless and hurtful, your decision was wrong. It's your responsibility to make amends and do what's necessary to make sure you make better decisions in the future.
But you are not a bad person, you made a mistake. No matter who your bf is commited to in a relationship, that man will make mistakes. Maybe this mistake is one he can forgive and stay with you through, maybe he can't forgive and continue on in the relationship -- that's his decision. But whatever his decision, you are defined by the totality of your behavior, not one event. How you respond now is important to the future of your relationships. Are you going to sit around wailing that you're a bad person or are you going to do what you have to do to behave the way you know a good person behaves?
I may have just lost the only thing in the world that I cared about. And I don't know why I did it, but I did. And now I've lost everything.
If your actions have caused you to lose the only thing in the world you care about, and you don't know why you did it -- don't you think it's time you find out why you did it?
You cheated on your boyfriend last night and this morning you're feeling sorry for yourself that you screwed up. You're not the victim here so why are you feeling sorry for yourself? Or are you, as much as your boyfriend is, a victim of your own behavior?
This isn't your father hurting you, it's not a boyfriend hurting you ... you are hurting yourself. The good news is that means you have total control to stop the hurting; but the longer you wait the harder it gets.
Stand up and face your mistake, clean up your mess and figure out why you set off a stink bomb in the middle of a relationship you value. It's time to get to work, not boo hoo over what a terrible person you are.
You are good and valuable man. Live up to yourself.