Endiku, I'm so sorry you had to do that. I was almost in tears as I read it. It's a very hard thing to do. You did do the right thing. It's going to hurt for a while but without you, the kitten would have suffered more than it needed to. How's your hand?
And going off of what Demonwolf said, I don't remember where I heard this but I like to say this quote to myself whenever I get angry at the world because of how it's run and how people choose to live it.
"Be the change you want to see in the world."