HI Kristen,
Since he was lying, cheating on you & treated you horrible, you should not be too surprised that he just walked out like that. I'm not telling you this to hurt your feelings. But since he was not a decent, good man to begin with, why would you expect him to all of a sudden do this in a mature, compassionate way?
Kristina had alot of good things to say to you. There is no ideal breakup. But people should treat the other person better than that. At least do it face to face in person. It does hurt alot. But from what you said, you are much better off without this man in your life.
Try to learn from this experience as to why you kept putting up with his bad behavior & treatment of you. Now, that you went through this you can know for sure what you don't want in a relationship. Don't be surprised if he tries to get back with you. I would not do that, if I was you.
The pain will be less as times goes on. Treat yourself real good & with alot of kindness. Good luck to you. Judy K.