That's the wonderful thing about marriage when its healthy is you dont' have to worry about these sorts of things happening.
Ken... This is a very difficult point in a marriage, and you do have my sympathies...
The more you sit back, the more this affair is going to progress.
My advice has always been to deal with OM as aggressively as possible short of physical violence.. public humiliation being one of my favourites...
However in the spirit of generosity to views i do not in any way agree with.. this thread being a particularly fine example of addiction starting up and taking shape... I would warn you to be careful when taking an aggressive stance, as this can lead to undesirable consequences.
In short Ken, you need to roll some dice here and decide if you want to try being nicer to your wife, or more aggressive with OM...
My recommendation is with the latter based on my research of these topics... but its completely your call.