I know how you feel, and believe me - age has nothing to do with it. I'm 28 and went through all of it. Wanting him, wondering how he could just move on while I was sitting at home crying my eyes out, which eventually turned into figuring out that he must not have loved me as much as I did him, and then also realizing that I was important to him he would have tried to reconcile like I did. The first two weeks were the hardest, and finally my pride kicked in and I decided I had to come to grips with the fact that it was over, and try to get my life back.
I know it's a cliche but it's true - time heals all wounds. I won't act like I don't think of him sometimes but it's been almost 4 months and I can't believe that I am doing so well. I thought I'd never get over this but I guess I'm stronger than I thought. I'm even going out on dates! (Some good, some not so good, but still...it's progress.)
Anyway, keep coming back to this forum and reading other people's stories. I hate to say this but you'll always find someone who had a worse breakup story that you did and that kind of helps to put things in perspective. That first two weeks I was on this site every 10 minutes (so glad I didn't get fired) and now I just check it periodically to keep myself in check. It really helps to hear how other people go through this time period. The links are good too.
Best of luck to you...you'll be fine, promise.