So what is the proper way to deal with a demand that you never react, never get upset, never do something that makes them react negatively, and always be aware of how your reaction is going to make them react?
Great question. Complicated answer.
First, the way your spouse reacts has everything to do with her current feelings and nothing to do with your answers. However, if you get frustrated, then her reactions are based on your reactions because she's already struggling. In a nutshell, your frustration is taken as saying, "I can't stand you and I have no idea why I even bother with this relationship."
Now, that's not what you're saying, but it's what she's feeling. This is all about feelings here; feelings are reality just like facts are reality.
For instance, if you feel like you're going to throw up, it feels horrible regardless whether you actually throw up or not. She feels that same way from a mental standpoint.
So what do you do?
Let's back up here. You asked something, she ignored it. You asked again, she ignored it again, and then followed up with an unrelated question.
Her ignoring you is a major sign that her brain is working overtime on something. So if you double down at that moment, she's going to think, "What a jerk- can't he see what I'm dealing with?!?" And of course you can't, you're not a mind reader. But it's important to catch these subtle cues that she could be thinking in a disordered way...or at least heading in that direction.
Step one- if she ignores you, back off. Now's not the time for discussion. It stinks and it's unfair, but it is what it is. Just walk away for a few minutes and let her internal crisis pass.
Step two- she asks a question that you know nothing about. Don't you wish you would've nailed step one? That's okay though. Give an honest answer like, "I have no idea, but I know who does." Then ask Google or Siri. You do have the combined knowledge of the history of the entire world on your smartphone, so you can deliver a passable answer in about 2 seconds.
Why does this work? Because you're choosing her and her problem over yourself. Doing the opposite leads to chaos, so do the smart thing and try to help (or get better at step one).
Step three- maybe she's still frustrated, which again is a clue that this isn't about you AT ALL. It's about disordered thinking and mental illness. If you make the effort, then she's mad at the imaginary thing. If you don't make the effort, now her rage turns to you. So you make the effort. But if that fails, then step three is to go back to step one. Say something kind and retreat!
I know this sounds childish and moronic. Yet it's my go-to for any conversations that begin to unfold this way. And it works about half the time. For the other half, I'll apologize for her struggling and offer a hug or some ice cream. That usually avoids the lion share of the drama.