Twinkle,
Wow, you've got a lot going on, chica.
I am so sorry that all this is happening at once... but it will only make you stronger, TRUST!
1. The good thing is that FI is okay. First and foremost, that is the big thing... that he was not hurt.
2. That is so crappy about your MOH. WTF? And call me old school but over an email is even LESS considerate! Don't talk to her until you have calmed down a bit. I would be upset, too. One of my best friends & bridesmaids also told me via email she couldn't come anymore (due to giving all her cash to her boyfriend - they've since broken up). But I just told her that I didn't hate her and understood and I know that she feels really badly she cannot go.
3. Don't listen to them. At all. Block them out of your head. If they say something, tell them that the longer they wait to book, the prices increase. Everyone knows that. if they can't make it, too bad. Seriously. They knew about it from the get-go. And the joy of a DW is that not everyone can come so if they are going to be "debbie downers" then you are prob better off without having them there!
4. Call your WC's boss and tell them you mean BUSINESS. Your wedding is fast approaching and there is no need for her to not respond to ya!
5. Hang tight. Just wait and see what happens at work. See if you can get some 'inside info' from the higher ups about what direction the comp is taking and then if it sounds grim, put your resume out there. That never hurts.
What resort are you getting married at?