Wow, BrotherMan, Doesn't sound like much fun on the homefront. Bummer.
It sounds to me like your wife really needs to work on the communication skills. And it IS a skillset, you know. Some people come by it naturally or were fortunate enough to learn them from our parents as children, but many or most of us have to really work at it. (Myself no less than any other.)
I'd like to make one observation, concerning this business of her being evasive when you can tell something is obviously wrong and are trying to open the lines of communication, then exploding over something small. That's bullshit. Unacceptable. I suspect there's something else going on there.
Im not going to say anything else, because I have strong feelings on this type of situation, where infidelity (aka disloyalty) is involved. But I still wish you both the best possible outcome, whatever that may be.