Pack his bags and take it to the OW's house. You need to do something drastic to wake him up.
Why did he claim he D'd in the first place? You can see that he never worked on himself during those other marriages and is still blaming others (YOU) for his happiness.
M-43 W-40 2D - 9 and 5
Emotion, yet peace. Ignorance, yet knowledge. Passion, yet serenity. Chaos, yet harmony. Death, yet a new life.