Don't wait for an apology, I know its like one of those times when your parents say. . . "do as I say and not as I do," but you can't let it slap you in the face everyday.
What finally made me forgive was my perception of being vindicated. I finally felt like wow she really messed up and she finally admited to it, but letting go of the anger was my own choice. I knew that she messed up. Why did I have to wait ten years and an apology to not let it bother me? To be honest, she did me a favor. I could have still been with her, miserable as all hell, but now I have a chance to find happiness with a much better person.
THe point of the ten years story is that you are going to stop being angry at some point. Believe it or not, YOU WILL NOT ALWAYS BE ANGRY. You can choose to let go of the anger in 10 minutes, 10 months or 10 years.
There's the rub, it's a choice. In a way you have to trick yourself. You have to trick yourself into believing they apologized(assumng they never will) You have to believe that you are better off without him or her.
In essence you have to dig deep and let go of the anger before you get an apology, otherwise you're just going to make things harder for yourself for the next ten years. Is that what you want or is that what they wanted? If you being angry and miserable is what the other person wanted, then if you chose to remain angry and miserable--They win.
This person did you a favor. Now you can find someone to be happy with, but you can't do that if you keep holding on to the anger and resentment. I hope that helps.