How do I clean a disgustingly dirty kitchen floor?

Bleach will, unfortunately, damage the floor. Linoleum is made of natural materials (unlike vinyl) so anything too acidic or alkaline isn't great. Get up whatever you can with a broom or water dampened sponge first. Most linoleum floors are waxed, so it's best to use a good ph neutral all purpose cleaner. Dilute it with water and mop it. That will clean and remove the odor. Since it's hidden under the fridge, moving to a harsher method like lemon or orange cleaner might be worth it. It's likely that there will always be some sign of the stain, but at least you wont have to worry about germs, mold or other growth! :) Good luck!!