It's a good thing to feel sad about it, it wasn't a good situation but next time you'll know to take a more humane approach, don't listen to the idiots egging on the torture and murder of non-human animals... they're shallow minds don't comprehend what it means to actually be a human and recognize the importance of life shared with all things on this planet.
Indeed, people like the OP are so rare these days... humans with compassion for the other animals on this planet, no matter their size or seemingly meaningless existence... fact is all of our lives are of equal value.
Now if only everyone would share that same compassion.