He knows this bothers you, that is why he does it.
Show him it does not effect you.
It is a way for them to feel in control.
My ex brought the OW to my house one day to pick the kids up. I smiled and acted like everything was fine. You should of seen my ex's reaction. It was priceless. He was so pissed that I did not get angry.
They are idiots.
Me: 46 H:44 Together: 25 years Married: 20 years Separated: 11-30-06 Divorced 12-21-07 OW: EA began 2005 PA began end of 2006 3 children,20, 16, 6 ex asked for forgiveness 01/16/11