Lizbeth,
I was first going to jokingly say you should pull the freaking-out "who is this other woman whose shoes I found" routine, but I think you have an in to the topic. You owe the man an apology for snooping into the history of his web browser. It's not the worst offense, but if you snooped, you snooped. So maybe you should begin by apologizing and then ask him "what is this all about?"
If the CDing doesn't make a difference to you, be sure you let him know that. Most of us who have a significant other are/were terrified of losing her. The others deeply want a wife/girlfriend who understands them. The reassurance from my wife that she loves me and will keep me, lingerie and all, means the world to me. I don't know what I'd do without her.
Problems that are ignored or minimized before marriage do not go away once the marriage begins. Even if you end up calling off the wedding the day beforehand and sending back all the presents, it's better to explore all the issues you can now, while both of you can go your separate ways if need be. I've heard that half of marriages fail. You can improve the odds that yours lasts your lifetime by dealing with the issues beforehand.