pinerunner:
Pay attention to what Dave Marten posted.
Until your wife, or anyone else for that matter, feels safe and secure, her brain is effectively shut down and closed. Logic is not going to work.
Flight instructors have to deal with this all the time with some primary, and sometimes advanced students. Even some people that want to learn to fly and are eager to jump in the cockpit do not feel safe at first. When that happens, instructors must recognize the issue with comfort and feeling unsafe, and deal with it. Until a student feels safe, at any level, learning will not take place. And the answer is not logic and stats. The answer is as Dave said: Short flights on nice smooth days, low stress, no destinations that must be met, etc. etc. etc. Until she feels safe, however long that takes, her brain is not going to respond to anything like stats. We are dealing with feelings here.
Just curious, how many hours and ratings do you have? You might consider having a flight instructor fly with you and her for a while to help her get comfortable.
Good luck!