I just wonder by your W saying "why did you find it so hard to be nice to me" she may have been giving you an opening.
Maybe. To me it feels like a trap... "When did you stop beating your wife?"
To even answer is acknowledging that it is hard for him to be nice to her. And if he answers the question, well, it won't be nice to her, either. Either way, he just proves her point, in her mind. Of course, not answering will make her mad, too.
