My first real relationship was with a guy I dated in high school. We dated for almost two years, on and off. The relationship got pretty messy at times, mostly because we were both so young and he didn't really treat me the best. He did some pretty awful stuff to me (as far as lieing, cheating, and just saying really hurtful things), yet I kept taking him back because I was "in love" with him. At the time I thought I was, and hell I could have been. When we broke up I felt like I was dieing and I was very depressed. All I could do was think about him so when I got the opportunity to take him back I always did. One day I realized that no matter what that boy was always going to be the same, and he was never going to be good enough for me. I realized that just because HE didn't feel the way I felt about him, didn't mean I was a loser or sucked at life. I ended up breaking it off with him myself, and after I did I felt better. I immediately started to realize how immature our relationship was and how I could find someone so much better (which I have). I still talk to this guy occasionally, and we are still close friends. I shared a lot of memories with him so I enjoy catching up with him time to time, however as far as romantic feelings go I have none. Break ups are hard sometimes, but you have to think logically as well and don't let your feelings take over. If you can benefit from being without a person, then maybe you just weren't supposed to be together.
My first serious relationship lasted about four years, and I think I started getting over it before it was officially over. I knew for a while that we needed to split up, and I was the one who did the actual leaving, so I think in some ways that makes it easier. But it still took me months to really move past it. I'd say you need a good six months at least to really heal.