Let me say "Sorry for upseting anyone" in advance , just incase someone takes this the wrong way.
When I was younger I helped out on my Grandparents farm learning alot about the facts of life and death that goes along with raising animals. My Grandparents both came from Farmer stock back many generations and what I saw was how they did things the "old way" . They drowned deformed or sick chicks as soon as they were born if needed. They would break a chickens neck to put it down if it was sick or injured , not try to "save it" because it was not how they were taught a good farm was run.
They did however take good care of all livestock on the farm and had a vet look over them twice a year to be sure of the over all health of everything on the farm. They had two flocks of chickens, one for eggs and one for meat but both were cared for equally as the other and in excellent health. We would kill 150 birds in a day with the whole family helping with the killing, plucking, and dressing out the birds. They would do the chopping block method for the killing and I helped with the chopping and plucking.
I believe the birds to be what they are,"food" not pets or members of the family. I had my favorite birds back then but understood why they were there. You just have to keep telling yourself that you are raising a food source for your family and doing it in a more healthy way without having to worry if it was sick or full of chemicals that aren't healthy for your family.
I'm proud of you and others like you who have the guts and forsite to look out for the well being of their family by taking the steps to insure they are eating healthy home grown food!!
If you have done right by the flock of meat birds and insured a healthy bird for consumtion then you have
Nothing to feel guilty about. Pat yourself on the back for a job well done and enjoy the fruits (meat) of your labor.