Sadness, remorse, compassion, its hard to really find a precise word for what i feel after i kill something. The immediate reaction is happiness, elation even, but this is quickly tempered by the fact that i have just taken something's life. Now i certainly don't feel like there is anything "wrong" with having killed an animal, especially if it was a quick and clean kill, but it is still something to be taken seriously. Additionally I always feel it is hardest when you see the animal actually die right in front of you, i would rather they run off a short distance and be able to die without me standing over them.
The absolute worst was about 7 seasons ago it was the opening day of shotgun season and a nice little fat 5 pointer snuck in behind my stand, and i ended up taking the shot with him 12 paces away from the foot of the tree i was in. Needless to say those 3 inch copper solids drove him into the ground, but he immediately started thrashing his front legs and bawling. Maybe i'm a wuss but i'm telling you that was the most heartbreaking, desperate sound i had ever heard in my life. He then started gasping for air but he had no lungs left and when he would exhale you could hear the hair coming out of the entrance hole behind his shoulder and it was making a small piece of skin flap. This whole production only lasted maybe ten seconds, but it seemed longer. I remember sitting there in my treestand saying something like "shhhhh, be still little guy, just go to sleep" over and over, haha...very emotionally conflicting for a 17 year old!