Mike, your words are the same ones I have, but they're stuck at the tip of my tongue. When it matters, like the situation above, it is usually the words that fail me. You are also right on about me justifying my wife's actions. It comes from guilt that I allow to creep in.
In the situation above, I tried to stand my ground as long as I could, without me loosing my cool. In a sense, I am glad that she was mad due to my persistence, and not by my anger (usually how I respond to boundary-crossing). I didn't raise my voice (I don't think) and occasionally stopped between sentences to recollect myself by saying "Okay...(insert my wife's name here)". I don't know how much of standing my ground I would've needed to get further information about who or where the doctor is. Considering how things were rapidly deteriorating, I decided to stop. My son was there too and keeping it up like that was no bueno.
My mind is mostly at ease now. Keep on truckin', aye? Today's visit to the doctor is another thing I've added to my prayer list. No turning back, only forward.