Ok, this is what my original post SHOULD have said (The real original post is in quote in a response below, and is long and rambling.)
After some of the advice given here, I have a new perspective on the problem. It crystalizes to this:
My MOH is my best friend who asked to have a central role in the wedding, and wanted to be first in line for any "wedding stuff," because she wanted to be involved. She even asked me to not let a specific other BM take over with any planning details because she wanted to be front and center.
For the last two months she only calls me with her own problems and won't even talk to me about wedding stuff. When I confronted her and tried to talk about wedding specifics (because other BM were offering help and I didn't want to undermine her and accept their help without giving her a chance to be in charge) she got upset like I was bombarding her.
My FMIL won't come out and say it but she hates my guts because I am an atheist and she thinks I've corrupted her son (he was also an atheist long before I came along but wasn't as vocal about it). She tries to change every detail of the wedding and insists on weary a dress that is the same color as mine. I believe this is because she opposes our secular wedding on principle. I have tried to go to lunch with her or have her over for dinner so we can discuss our differences peacefully, but she refuses and changes the subject whenever I try to bring it up.