I think everyone experienced what you're going through. Someone wants described it as your brain having anchors to the memories - so it's difficult to move on because you remember that you used to talk a lot, go out a lot etc and now when he's not there there's a void.
Anyway, there's a few things you can do:
- Visualize - just close your eyes see the person in front of you and see that there are ropes connecting you - cut those ropes in your mind and set him free. You can also perhaps talk to him and set him free in your mind.
- Write down your wish, for example, you need help letting him go. Fold the paper in four and burn it. Watching as the smoke goes and knowing it's going to the angels and they will help you.
- Setting a candle, I've done it with 2 exs and with one of them it helped, not so much with the other (but it was a much much stronger bond) - http://www.missionaryindependent.org/candle-altar-cut-and-clear.html - this is the site I used. You basically write in your petition that you would like to let go of X and it's also a good idea to write who you'd like to meet/enter your life instead.
Best of luck!