Have you attempted to establish a boundary of "no contact with OW from inside of our home"?? If he wants to go outside on the lawn and call or text her from his cellphone, or go to the Starbucks and mooch some free Wifi, then knock himself out, but NOT FROM INSIDE YOUR HOME.
I disagree with the suggestion of "go out and do something fun" when he goes online. This is YOUR home; you should not have to leave it to enable him to carry on his emotional online affair unfettered!
