when I am arguing with my W over her feelings, I am not telling her she is wrong to feel that way. I am telling her that what she thinks happened, or thinks I feel, that CAUSED her to feel a certain way is incorrect.

It's all in the way it's phrased. The message she gets could be "You're wrong to feel that way", which would be invalidative. When you get to read the Lundberg book, that will help you see how to help other people figure things out on their own rather than you telling them in a manner they may be defensive against. Also try "Feeling Good - The New Mood Therapy" by David D. Burns.