My wife is cheating on me - nothing new I guess. She is secretly seeing a guy who I’ve known for 30years. He is disliked by most and he is with a partner of ten years having cheated on his wife to be with her. He ingratiated himself with us, took me to sporting events etc. and we began to see them as a couple and would occasionally socialise. She has now left, the kids are with me, she is seeing him secretly and sending him explicit messages and pictures, but he is still with his partner who is ignorant of what he is doing. He also has a woman he sees in London who he has been seeing secretly for many years (I know her brother). Do I tell his partner about his affair with my wife - and share the detail of the when and where....?