I sympathize with you. I hit a squirrel once and to this day I still can remember the circumstances around why I hit it and how I wish I could have avoided it. Sometimes there is just nothing you can do to avoid hitting an animal. Deer at night can be especially hard to avoid if they just suddenly jump out in front of you from the darkness. It’s nice that you have such a caring feeling towards animals. I’ll pray for comfort for the deer and hopefully it ended up okay.