I'm sorry, Joey. I grew up with a menagerie - dogs and cats and horses and goats and whatever else you can think of. My father taught us that we were responsible not only for their lives but also for their deaths in the sense that were must make sure there was no suffering at the end for them. He was not a religious man but he took the biblical message that humans were stewards to the animals very seriously.
I have fostered special needs animals for most of my adult life and I have had to make that decision many times. I wish I could tell you it gets easier as time goes by, but it doesn't. Every animal I have lost has left a mark on my heart. What I can tell you is this: all life is finite, and to have something that loves us unconditionally during that life is a gift beyond value. We speak about the unconditional love our pets give us, but we don't always recognize how much we love them and what that teaches us. We should, because that love is infinite.