How can I fix this emotional mess?

I think to tell your husband something like this is bound to make him concerned about your feelings for him as really you shouldn't feel the need to tell him something like this. This sort of thing you should share with a close trustworthy friend not your husband if you feel that strongly you need to talk about it. As for what to do don't bring it up with your husband again and if you feel its possible I would apologise to him for the way you reacted. Then talk to a friend about it to try and resolve the issues you have with with this ex in your head. I think you need to get your head sorted over this one as it could have a longer term impact on your relationship as really your ex shouldn't be an issue now to this extent.