Most Helpful Guy
Despite popular belief, one needs to invest as much effort in getting over a love as much as they invest in building it. You need to first accept the fact that you two are not meant to be for the long haul. You have loved him as much as you can love him, and you have given him all that you can give; however, you two just are not a good fit for one another.
You are not alone though, the finality of realizing "it's actually over" more times than not influences many of us to hold on longer or stay in relationships far too long when we know we have no business doing so. We simply stay because it's comfortable and convenient to do so with someone that we have a history with.
That said, I encourage you to follow Madhatters4 advice. Occupy your free time. Stay busy, join a gym, hang out with friends, site see, go dancing and interact with guys that you find attractive.
Also, if need be, remove any sentimental items that remind you of him. People often stay emotionally attached much longer than they should, because they hold on to pictures, gifts, clothing and other items that remind them of their former partner.
Last but not least, tell him that it's over and stick to your guns. I have a suspicion that once he accepts that it's over as well, it will be substantially easier for you to let go.