I will not defend your wife by any means. Please don't take what I am going to say as defending.
In any relationship where there is cheating most of the time there are issues in the marriage. Something one partner or the other is not getting that they need. I would suggest marriage counseling first rather than end a 14 yr marriage. I do feel for you. I have been cheated on and yes there was something lacking in the marriage. We are all here for you any time. Good luck. Welcome to pc!