aww I'm so sorry.
I'd be the same way. That kind of thing just gets to me.
A couple years ago I walked past the tree in my old neighbor's yard, and I hear this spastic kind of chirping. I look under the tree and there is a little tiny sparrow (perhaps a baby?) laying on the ground - his neck was broken. There was nothing I could do, so I had to leave him there. But I went inside and I could still hear him from inside the house, until eventually it stopped. I've never really gotten over that.