Why can't I seem to forget about him, no matter how hard I try?

It's been three months since the last time I saw him. You'd think that once he graduated from high school, I can finally get over him and move on with my life...but boy, am I very wrong about that. We have a lot of mutual friends. I have to sit in the same classroom of the same school as last year. I still remember the moments we shared. I still know every single song I've ever dedicated to him, even if it's long gone from my iTunes library. I still know his favorite songs, favorite artists, favorite color, catchphrases, his face and his voice, his birth date (even the day of the week he was born), his siblings' names. At first, I didn't even want to TRY to move on. Few months later, I'm actually forcing myself to. Until now. I even divert my attention to other guys. Unfortunately, as usual, literally EVERYTHING reminds me of/seems to bring me back to him. (The last guy I dated had the same favorite color. The day I met this guy and the day he called me his girlfriend put together is the day I fell for the first guy.) (The latest guy I've gotten myself involved with, on the other hand, does the exact same sport as the first guy. And like the first guy, has serious trust issues and a serious fear of getting hurt, therefore they both thought it wasn't a big deal to toy with my emotions.) I even went as far as blocking the first guy on Facebook just to forget him. Unfortunately, my Tumblr weblog is pretty much dedicated solely to him. FML