I don't think you are a bad person for having these thoughts. They are perfectly reasonable thoughts to have in your situation when you have questions.
- What about you and your desire to have kids one day? Are you willing to give that up for this?
- Are you free / emotionally free to date other people?
- What about the TMI line and him telling you things that you may or may not want to know? Are you happy knowing these things or troubled?
- What about them making life choices/decisions that influence you in some way (like a new child) without even telling you anything was up? Do you want that to change or are you happy with that?
I don't know how long you two have been together, but it doesn't sound like you talked it all out before, or kept talking along the way.
The beginning doesn't sound auspicious either.
He wasn't really interested in it at all. He only started the whole process to make things seem "fair" and he wanted to give her what she wanted.
And then this...
But part of me feels like this is not the way poly is supposed to be.
What WOULD poly be for you if it was the way it was supposed to be? What would you want? And how far removed is it from what you actually have?
You are responsible for creating your own happiness and what you do/do not participate in.