Some help with getting over an ex?

I was with my ex boyfriend on and off for 5 years. I basically was with him during pinnacle times in my young adult life. We constantly fought and he was very sedentary. I was extremely social. We decided to end it because I felt he wasn't telling me the truth (which he wasn't). I now have someone who is everything I could of asked for. Has a way better job, family/friend life, and is down right crazy in love with me. Yet, I still think of my ex. Could this be because I spent so much time thinking of him before that it is difficult to let go? I was with him during all my failings and my accomplishments. But, I would love to live my life with my new boyfriend. Any ideas?