TM, I will chime in here...

I do not regret moving out. Some think that being apart would be harder than staying in the same place... I don't know about that... I couldn't imagine what it would be like to live under the same roof as my W, knowing full well an EA, and possible a PA, was going on.

I moved out for additional reasons. I am better for it.

The point being, once I moved out, there was no need for my W to "sneak around". Even though she was doing a horrible job of it while I was still living there. Moving out didn't enable her nor did it condone the EA. But it certainly would have made it easier for her.

As much as I'm sure it really hurts to be witness (hearing) about the continued EA, you are still in a position to be the man only a fool would leave.

I'm not exactly sure how you might say it, but I'm thinking something along the lines of...

"W.

While I appreciate that we are living under the same roof simply as room mates, it is still difficult for me to overhear conversations you have with (state OM's name, if you know it).

I ask if you could be a little more discreet with your conversations, as I am still feeling sensitive about it.
"

That might sound too forgiving. Like you're condoning the EA. It might be the best option, though.

If you tell your wife to pack or drop OM, she may choose packing, as Denver suggested.

If you tell your wife to drop OM, she is likely to just think "screw u. I will do what I want."

You could affirm you do not condone the EA if you feel you must, but if you simply assert your feelings, then you possibly put you into the EA equation, every time she picks up a phone to talk to him. This could have benefits in many different ways.