Thanks!
I've been engaging in some serious Google-Fu since the mishap and apparently this brand of aquarium thermometer is pretty much aquarium safe if it breaks (and it apparently breaks easily since there's a lot of google results on it lol..)
The liquid inside is alcohol or glycerin based.. I imagine with a 75% water change and the fact the liquid was more than likely not pure alcohol. The amount in it is probably negligible compared to the 40+ gallons of water in the tank. This is the part I'm really worried about but I am hoping the water change diluted it and it's harmless.
The little metal balls did fall out too but I picked those up with a magnet.. broken glass cut my hand, oh well.
I have to admit I am kind of bummed out right now but I think it will be alright.
EDIT: Yanno what? I may be freaking out over nothing. I just looked at the broken thermometer, the red liquid part never broke, just the part that held the little stainless steel balls to weigh it down. Ahhh.. I can sleep tonight.