Whatever you do, take some time to cool down. Confronting her when you're filled with anger won't do either of you any good.
I do think that you should confront your W. But first you need to take a full day (or better yet, two days) to collect your thoughts and think about what you're going to say when you do confront her. People on here, including me, will help you with that.
For now, collect whatever "intel" you can and keep a good record of it. The more evidence you have the better, because people in affairs ALWAYS deny, deny, deny.
I'll write more soon, but know that you're not alone. About 2 months ago I went through the EXACT thing that you're going through.
Me: 33 WAW/MLC: 33 M: 4+, T: 10+ Separated: Nov 08 A#1: Oct 08 - Jan 09 (exposed and ended) A#2: Feb 09 - ? 1: http://tinyurl.com/mrmistakes 2: http://tinyurl.com/ckch9t 3: http://tinyurl.com/stillwaters3