
I find it helps to consider my meat birds like produce grown in the garden. I can tend carefully to their needs and provide all their nourishment & water, especially when they're tender little things. I can take pride in their growth, and find myself spending time just gazing in admiration of their natural beauty. I anticipate the delicious harvest as they grow and ripen. It would be a shame to let it all just wither & die on the bush because I couldn't bear to pick it to eat it. It's somewhat the same with your meat birds, they're not going to live much longer after they're fully grown.
The main difference, of course, is the premeditated taking of an animal's life, something that can be quite daunting for the uninitiated, something outside the experience for many of us in our modern urban culture. I wish your FFA could give you more support & help for this aspect, especially for your children. It would be great if you could find someone in FFA or BYC to work alongside you during your first processing session. I'd be glad to help if you lived near me!
And you know your kids best. If you really don't think it would benefit them to take part in the processing, don't push them. Some kids jump right in and do great, but it could be really traumatic for others.