I know EXACTLY how you feel. We did this about a month ago - took me several days to get over the images in my head even though I knew I did the right thing and felt a sense of accomplishment AND fed my family. I think everyone should have to experience how difficult it is to take a life to eat your meat. I still get a little sad when I see their baby pics... they were all named as they were professionally sexed and supposed to be our pet layers - bad sexing gave us 5 roos to cull. My husband had to walk away for a few moments after the first 3 - it was getting to him, but he finished the job. It's good to know you did the right thing and you know that, if needed, you could do it again.
Watching culling videos on YouTube seemed so simple to cut the coratid artery. It was. NOT easy at all. My first attempt left him bleeding, not dead. In the end I was successful. But you are right, the images in my head are so vivid. My 15 year old daughter stood by my side each step of the way, bless her heart. And my 18 year old helped me, in the way of directing him towards the capture net. She went in the house before the cull happened. She knew it was not going to be easy, bless her heart. So she babysat or 6 new chicks for me. My hubby works the night shift, so he wasn't available to assist. I'm grateful for my neighbor who came over after the cull to assist us in the plucking and cavity cleaning. I learned so much today! And I'm proud of my accomplishment.