I had a dog pass away a couple years ago...we knew he was sick - he was also old...but we didn't make him die in pain, we humanely put to sleep...I find it hard to sympathise when you made the cat die on the bathroom floor...
I had anothe rincident when a stray cat that frequented our house got into antifreeze in the garage...it was having seizures in my arms and we took it to a vet - called in an emergency case they put it down..I dunno...maybe i think too much