I have never intentionally hurt an animal either. I understand your feelings as I would be in the same place. But, you have to live with yourself and see yourself in the mirror. I would agree that have a heart trapping and bring the cat into the humane society as a stray might be best, You should not, unless you can easily afford, pay for the neutering. The Humane society will neuter him and find him a home. If his real parents come for him they can claim him. Don't leave your real name or address when you leave him off.

Sorry to hear about your kitties.