It took me a couple of days to find the right word, but I finally did figure it out. I'm not sad, I'm not mad, no... I'm disappointed.
I got an email from Jessica Kingsley Publishers a couple of weeks ago saying that, if I got more perspectives, more writers, involved in my book, then they were interested in publishing it. I emailed back saying that I could work with 3-5 other people and have each question have several answers and put it together that way. They emailed me back yesterday saying nevermind, they don't think the book would be useful to readers and would not be offering me a publishing contract.
That's it. No more to the story. No happy ending. I can't decide if I should continue to work with the people I've found or if I should just give up. I don't know how similar pubslishers are, if other publishers will think just like this one does. When it's just myself working on the book, it's one thing to do writing that won't get published. But when I'm working with 5 other people and asking them to write something that may never get published, I suddenly feel responsible for their disappointment too.