Sorry to hear that it went poorly :c. I just wanted to throw in my two cents, seeing as I've been in a position similar to that of his wife. My partner was really pressuring me to meet the girl he was seeing, he was doing so under what he thought was the best intentions. This was my first experience with poly so I was still trying to process everything. I heard A LOT about how much the two of us would get along.
But the fact was that I agreed to meet her for HIM and I was not ready for it. I was polite but the fact was that regardless of how nice she was I had been pressured into meeting her. You're partner's wife may have been feeling the same thing.
Meeting your husbands "other", if you'll forgive the term is always hard the first time. I don't mean to excuse her for being rude to you, and I don't know at all if she was actually feeling this was but it's something to think about.