My late sponsor used to say, "You're right where you're supposed to be." Yeah, pissed me off when she said it to me, too. But you really are. Breakups hurt, and they hurt even when things haven't been going well, as long as you had the hope that things might take a turn for the better.
All you can do is keep moving on. It WILL get better. What you have to be prepared for is that if the grass, for him, turns out NOT to be greener on the other side, he may come back with all kinds of promises to change and tearfully swear you were the best thing he ever had and now that he knows it, yada yada. You get the idea.
This won't NECESSARILY happen, but if it does, you should be prepared with your response. Which should be along the lines of, "No, you were right. It's time for both of us to move on. I wish you the best, but please do not contact me further."