break up..how to stop

My ex and I just broke up after 5 years and I want to move on. I find myself trying to talk to him often because that's what I'm so used to and I obviously miss him. How can I just stop contacting him? I may sound crazy but it's like I have no will power. I wanna talk to him even if it means we are arguing...it's pathetic. I just wanna feel normal again. We were supposed to be getting married in a few months and we've been broken up for about a week or so now. Help!