I have to say that there has been some really interesting advice on here. The only thing I know to do is post my story and hope someone takes something away from it... the ONLY advice I will give to the original post is DO NOT GO SEE HIM. You will only be left feeling embarrased when he walks by and tells you he has something going on... I agree that you should live your life, let him live his and see if you are brought back together.
Okay, on to my story... I was engaged at 18. It was my H.S. sweetheart and I got all caught up in the whole "first" thing. Neither of us was ready to wed but both of us were scared to break it off. He ended up finding someone else (behind my back) and it created hard feelings between us. In the end, it was the best thing that ever happened to me. I was able to move on (even though I didn't think I wanted to) and go to the college events I wanted to without having to justify why I was there or getting the 3rd degree about what happened there. My last year of college I was set up on a blind date over summer break. The relationship survived the 500+ mile distance and we were married at ages 27 and 28 (despite both of starting the relationship saying we did not want to get married). By the time we were married, we both knew what we wanted in life and couldn't imagine finding someone so "in-tune" with where we were and where we wanted to be. I think the reason we lasted and have remained as happy as we are is that neither of us pressured or felt pressure to get married. It was never an issue. In fact, when he proposed, I thought he was being cute and giving me a peanut-butter & jelly sandwhich after I had to work late. Come to think of it, I never had dinner that night...
Okay - don't know if the message will reach the people that need it but oh well... my last comment is that age is not as big of an issue, as is maturity. While the sometimes are related, they can often be very far apart.