Dear {Recipient},
Perhaps the letter isn't the best way to go about this, but I really don't know if I can face you after what I've done. Maybe that makes me a coward. I don't know. I know that I don't deserve anything from you, but I can only hope that you'll read these words, knowing that I mean every one of them.
I am truly, truly sorry for what I did to you. I know you are hurting now, and I know that's all because of me. I promised that I would never hurt you like this, and I did it anyway. I was supposed to be the one who would protect you from this sort of pain; I never intended to be the cause.
I don't know if it's ever possible for you to forgive me, but I hope that someday you can find a way to do so. I hate that there's a chance that you will never want to be a part of my life again, so I hope you know that I will do whatever it takes to prove to you that I can do better if you just give me a second chance.
I hope to hear from you soon.
Always,
{Sender}
