I know that what she's asking us to do isn't unreasonable.

I dunno. Maybe it is reasonable. (I don't have this hangup, and I would be like, "What are we, five?") But it sounds from above, especially not letting you pass on the exercise, like she's being pretty unreasonable about it.

In a way that I'm finding pretty icky. If it would be useful for you for me to break down a bunch of the ways this rings "that sounds like an abusive parent" bells in my mind, I'm happy to do so.

But in any event, this isn't a forced choice between her being the unreasonable party or you being the unreasonable party. She can be reasonable asking you to do this, and you can be just as reasonable in not wanting to do it. For whatever reason. It doesn't even have to make you feel like you're bragging or any specific thing. It's enough that you don't want to and you feel pretty strongly that way. Maybe it makes you feel unsafe. Maybe it violates your religious beliefs. Maybe it feels invalidating of the difficulties you're having. Maybe you're having a cranky day and don't feel like being pressured into being positive for somebody else's pleasure. It doesn't matter the reason.

You get to say no. Just because you feel like it.