You can ask, or confront, but you may not get an honest answer.
Don't think of yourself as second option or that you are being "crapped on." Rather than seeing yourself at the center of this look at your wife and realize it's not you, but she who is having a problem. She's probably confused, maybe going through some sort of depression and looking to "feed" it with the biochemical changes (excitement) that one gets from an affair. It's sort of like someone testing drugs or using alcohol. Affairs are a false high, but people who are involved with them generally don't realize this and tend to get caught up in them.
Other people might disagree with me on this, but I believe exposing affairs is good because they thrive with secrecy. However, I also think one needs to be careful how they do this. If you blame or shame them, and do things that makes them feel the situation is being "rubbed in their face," this may tear the marriage apart. I don't think it's wise to go there.
Probably your best bet, since this is a very emotional situation, is to read, reread and reread (have I mentioned reread?) Divorce Remedy and Divorce Busting over and over and over until you know it intimately, emotionally detach, work on yourself, GAL and focus on your kids.
There is no arriving, ever. It is all a continual becoming.
