I think you did fine, and its normal. I've felt similar things. I think one of the posters really hit the nail on the head, when they said they would be concerned if you DIDN'T FEEL some of these things.
I've bagged a few deer so far now, and all have been either doe's, buttons, or a spike. This year i bagged a beautiful 8pt buck. A few hours later, when it was hung up, and i was about to butcher it, myself and some family and friends were around. We were all admiring how he was such a beautiful specimen. Then it hit me, I kept saying I hoped that, the buck had passed on its genes this season. I said this more than a few times. I think the feeling is that he was such an asset to the population you want more like him out there. and by killing him off, you have just ended that. Then my buddy accurately said. He's 5 years old, of course he passed along his genes!!...That did make me feel better. But the feeling was still there..Bitter sweet, but i don't dwell on it. I know i try my best shots. I Know i try to utilize the animal to the best of my abilities. Its what i need to do for myself... seems like you feel the same way. I could only wish more people had the respect you do!