Welcome to CAF, Andra! :wave:
No one here can answer this question for you definitively. I would recommend talking to your parish priest as the best first step. He will give you invaluable guidance and point you in the right direction. Eventually, you will need to get in touch with the Tribunal Office for your home diocese, or, alternately, the diocese you were originally married in (if the two are different, you can pick either one).
"Annulment" is the popular term, but the more technical term is "declaration of nullity". Basically, the Church investigates to determine whether or not a valid marriage took place at the start. Thus, they will ask you questions and will ask for witnesses who can give them a picture of what was going on at the time of the wedding. Your ex will be given the chance to give his perspective, but, if he does not respond, the process can go on without his input.
From what you have described, there could exist grounds for a declaration of nullity, but it's something that needs to be investigated by the proper Church authorities. I would encourage you to pursue this. I know many who have found great healing through the process. Of course, prayer is key as well as an openness to accept whatever decision is handed down by the Tribunal Office.
I will keep you in my prayers!