Oh, Natalie, what a brave, brave soul you are! You pursued all other options and did the KINDEST act with love and compassion! I have had to be in that unfortunate situation since I was a kid and I still dread that I may have to do it again. Yes, I agree with the others that Superman is eternally grateful, and that now you have this wonderful guardian cat-angel.
As for expressing the graphic details, that can be a cleansing process - my vet is so understanding & will discuss this in detail with me, since she understands how hard it is for me to do. I hope & pray that you are finding someone else to share this with. You can PM me, if you like - I was raised around livestock, so not much will gross me out.
Thank you again for having the courage to do the right thing! Hugs, Susan