It is so important to be able to play with one's creative work. And the more your livelihood or identity depends on creative production, the harder that gets.
I love the idea of a beta reader dating service! And in fact such things exist.
Adding or subtracting a character in the middle of creating a lengthy work is nearly as challenging as breaking up with a longtime life-entangled partner.
You already made your work in the best way that you know how. Now you need editorial advice. That's part of the process for any writer, and being an editor in no way exempts you from it.
There are some projects where artistic urges outweigh commercial considerations, and this sounds like one of those.
The way you feel isn't a rational response to a defined situation, and can't be evaluated on that basis. Feelings don't stay contained and orderly. Some of your feelings may not even be about your writing.
Draw on the best of the way the world is and has been, as well as your most optimistic hopes for what it could be. The real world is very unfair to those on the margins. Use your writing to make up for it.
You're operating by improv theater rules, where as soon as a character introduces a new idea, you say "yes, and" to it. But this theater troupe answers to your direction.
Being blocked on writing that one is obligated to do is something we don't usually think about the way we think about being blocked on creative projects.
The question underneath your question is: "Am I allowed as a commercial writer to do the thing I want to do as an artist?"