Need serious advice....thinking of calling off wedding

I've often read your advice to other B2B's in turmoil and since I feel like I can't discuss this with my friends or family, I figured what the heck?

FH cheated on me when we were dating for 5 months, I found out when we were dating for 9. It took some time to hash things out, we never broke up but I never fully trusted him again until we got engaged. I made going out for him really tough by questioning where he was going, who is was going to be with and having him call to check in often. He understood why I did this and obliged without complaint. I truly felt that when we got engaged it was a turning point in our relationship, that there were no more trust issues, we were about to plan the rest of our lives together.

Lately I've been feeling uneasy like something wasn't quite right. I didn't think he was out there cheating (since we live together it would be more difficult than the first time) but still I felt a pit in my stomach. Two nights ago I found out that he had posted a personal ad on a, let's say non-reputable, web-site. He used all his actual attributes, height, eye color, hair color and even created an e-mail address for interested parties to contact him. I was completely and utterly devastated and in such shock I couldn't even shed a tear. I had to wait another 45 minutes for him to come home to confront him. I left what I had found on the computer screen for him to see and just crawled into bed. He saw it and came into the bedroom and I could not even look at him, it hurt too much. He tried to offer an explaination but I told him that I did not want to hear it because there is no explaination for this and that I cannot marry a man that I do not trust and I do not trust him. This made him begin to tell me how important I am to him, how I changed his life, how he never imagined he would find someone like me to spend the rest of his life with. But all I could ask is 'then why??' Why do something like this? He swears that he was not looking for someone else, that it was a stupid, immature thing that one of his other friends did and they thought it would be funny to see the responses they got. I do not find any humor in this, I think it is deceitful, disrepectful and hurtful!

We haven't slept in the same bed for two nights now and yesterday evening we stayed in separate rooms. He tried initiate conversation, but I was still to angry to answer at all. I try to focus at work to keep my mind off it but I just feel like crying at my desk and have to go to the ladies room to hide for a few minutes. I just keep asking myself what's wrong with me? What did I do wrong? The rational side of me knows it's not me. I just don't know what to do and the wedding isn't too far off.

Thanks for listening....sorry so long!