My husband admitted that he may have loved his first gf more than he loves me, what to do?

My husband said that he definitely doesn't love her anymore. She left him for another guy. This was about 5 years ago. Maybe 4. He was 18. She was younger but he was head over heels. He even promised her that he would never be with another woman and she broke his heart. I heard that it's bad if a guy is bitter about his ex. Well it's not like he talks about her all the time but I know she hurt him. And he won't promise me that he wouldn't remarry if something were to happen to me. I would though. I think that in an ideal marriage you should be able to make that promise. And he told me that he doesn't know if he loved her more than he loves me. What a crock. This really hurts me. I am so devoted to him. I mean he never talks to her, or any women but how can he have loved her more than me? Should I just get over it?