why can't I let go...

We were together for 4 an a half years and we split up a year an a half ago... we went through hell and back together. He was the controlling type he hated all my friends. Hated the fact that I went to parties when he didn't like that scene. I was a wild child. I had a drinking problem an he knew it and I never stayed sober so we'd fight a lot. And it was a back an fourth thing he'd cheat on me and I'd leave or I wouldn't give up the party life an settle down with him... and after I had my little boy he got worse I straightened up and he wouldn't let me go around my mom or any of my family he ran my step sister that died last year off for coming to see my son the summer before  and that has hurt me in ways nobody will ever understand. Butt back to the point. We had our good days and I was happy but the bad out weighed the good and I couldn't stick around.... like I said it's been almost 2 years an I can't go a day with out thinking about him... I can hear a song and want to show up at his house..I miss my little family more then Anything. But I just feel like I should be over him like I should be like him and moved on with somebody else and be happy loving my life. But it's not happened yet...