Already said a prayer for you this morning. For strength, clarity and discernment.
What helped me was to script out my 2nd, longer, "The Deceit's Gotta Stop" confrontation with my wife. Practiced it, over and over, even out loud, in my office. Rehearsed my body language, and my inflection, and my eye contact. Probably two dozen times.
It left me VERY prepared, and pretty calm. A 1/2-pill of my anti-anxiety meds took care of the other half nicely.
Another technique I use when nervous is to remind myself of all the ways that the OTHER person ought to really be the nervous one! And that's certainly true in your case. YOU are fighting the noble fight, and your wife is lying and fleeing and generally acting of poor character!
Who said this had to be a 15-second script? I'd suggest about a 3-minute one, give or take. If you can find me in the alt (FB), I can e-mail you the one I used when I re-confronted my wife, but it was a little bit different situation.
Back to April . . . uggggh. I'm so sorry, altho it doesn't surprise me. Do NOT blame yourself; it is not your job to "see signs" of things that no self-respecting man expects when he gets married. It is ONLY your job to respond, swiftfully and forcefully, once you do find out, and that you have done exceptionally well.