Melweb, I agree with what 2T said. I know it must be difficult, but you need to find a way to treat him like a roommate right now. He is confused. And he is trying to have it both ways. But more you get on his case to stop any contact with OW, the more he will be tempted to continue. Like they say, “the forbidden fruit tastes the sweetest”.
I would not do anything right now. Like we like to say here, when you don’t know what to do, do nothing.
M:50 H:52 S28 (my S from previous marriage) M:17 + 3 BD: 06/12 S: 06/12 - H works in another state