Dgtal, do you think that maybe this is misplaced resentment that should be directed at your W? That you are angry, and you would rather place ALL of the blame on this OM instead of aiming it at your wife because you are afraid she will get angry?
Im not saying that you should try to make your W suffer or anything like that, or that you need to direct this anger at her, but maybe you need to remember that its not just his fault that there was an affair.
I could be totally off track there, but I just wanted to put in a suggestion of what might be going on. An outsiders perspective sometimes can be useful.
I think that your idea of renewing your vows/or legally getting married is great. I think that often it can provide great healing to a wounded marriage.
I guess I gave the wrong finger to the wrong man...