What have I started?

OK, so winter has been horrible and the house has been locked up as tight as tight can be. Baseboard heaters = high heating bills. Anyway, I've been periodically keeping the bathroom fans on to keep the stale air somewhat circulated. Several weeks ago I turned on the fan in my bathroom downstairs and it sounded like someone stuck a screwdriver in it and the fan blades were hitting it with each circulation. Not a nice sound to here. I went to Home Depot and bought a new fan and have been driving around town with it ever since. It almost became a permanent fixture in the car. Today I felt somewhat ambitious (I don't know why) and decided I'd install it. Now as most of my family knows, I'm a handy woman at heart and will install or fix anything I can myself. Usually mom has some kind of project for me when I visit her :) (Love ya mom!) Well, this project had been a blast. Literally! It looks like I set off some TNT to get the existing fan out. It HAS been in there for 25 or 26 years, so it did not go willingly. Here's some pictures of the damage. Look at the gunk. GROSS! Needless to say, I did not finish yet. What a mess! Don't worry mom, I have been to Home Depot again and bought some sheetrock to repair the ceiling when I am done. I will post more photos of the finished project