if you couth your wife with another and you did it also (but she dididn't know it yet)
there are a few possibilties: 1) she DID know about it 2) there was difinately something wrong with the relationship for a while, otherwise you wouldn't go (both) on an sexual adventure.
more info on the person sitting in your wife's bed 1) it could be your best friend 2) it's your brother
how i reacted? normal... if i do it , she can do too..because the respect is gone. but if i go to another woman, the other woman will know this, because i sais this to her! and soo will i tell this to my wife