Having experienced something kinda similar, I know that sometimes I still miss my ex too. When I was 14, I started dating this guy and our relationship lasted 7 months. I knew that at that point he had cheated on my once (within the first month of our relationship to boot!) and figured I was better off without him. So we stayed apart for two months, and then got back together for another three or so. It was a very up-and-down year for me, and after all was said and done I found out that he had been cheating on me a lot more than I had ever realized or ever would have imagined. And although he never raised a hand to me, the emotional stuff was more than enough pain for me at that point.
My advice? Accept that you may always have feelnigs for him. I still do, and it has been nearly 6 years since i've even seen him, much less spoken to him! I rack it up to the fact that I lost my virginity to him, he was the first guy I ever loved as more than a friend, and losses such as these always hurt. But am I better off without him?
Much! I wish him all the happiness, but someone else can deal with his crap!
Best of luck!