Agree with Matt. Show that you go on and take care of what needs to be taken care of, and that you aren't going to become less of a man & H. In a sense, do you give her power to cause a reaction, which she will notice that she has hurt you, or do you show that you are above it. Certainly, go cold, but clean the damn dishes, especially if they are at least partly yours. Even if she is acting poorly, take care of your house and your environment.
Maybe clean the dishes, then go do something with friends rather than sitting around the house. If you do sit around, I agree with the don't wait up, turn the lights out, and don't leave out a signal that you've been spending your time focusing on her being out with the OW.
Like Matt, I haven't gone through this, yet. My W is going through an MLC, so as I've detached and she can no longer blame her unhappiness on me and our M, I'm expecting and steeling myself for her to start looking for something to fill the hole in her soul that is causing all her pain and unhappiness, and that this will likely be an A. It will still hurt like hell, and I know that I will struggle like you are. I've got the one advantage of being separated so I can get drunk and not clean the dishes until it is time to swap on the kids, but I'm damned if I'm going to react in a way she can detect that it is eating me up and causing me to seem less than highly functioning in going on taking care of life end of things -- I hope (we'll see when the sh*t hits the fan).
Hang tough, I know it has got to have your guts in a knot. Just thinking about it in regards to my W, does this to me. Keep sharing and we'll keep throwing you support to help you through it.
Me: 50 W:43 S6, S3 M: 12 yrs. T: 17 M is bad & Not happy Bomb Mar '14 S 5 Feb '15 D Bomb 13 Apr '15 (but "no hurry") DB Coach May '15 Wants proceed on D Aug '15 Starting 1-on-1 negotiations Sept '15