Doing the "right" thing sometimes makes you feel bad

In the thirty years we have lived in this house, many things have changed and we are soon to have renters on either side of our suburban quarter-acre block. The house to the south has been rented for some time, with different people in the front and the back.

The tenant at the back was a young unmarried mother with two children who loved to play her music loud at inconvenient times and she had a black tom cat, the only survivor of two she owned, who loved the sunny spots in our back and front yards as a refuge. He was quite nervous and making eye contact with him always caused him to shift elsewhere. We have no pets at the moment (we enjoy our children's instead) so we respected his need for privacy.

Three weeks ago, she did a midnight flit, leaving the place in a shambles (we know the owner, who has spent almost a fortnight repairing the damage and cleaning up the mess) and left the cat behind. It became obvious she was not returning and checks with all our neighbors showed that no one was feeding the cat, plus there was evidence he was subsisting on the local bird life.
As cat people, we were concerned, but we have very young grandchildren in our house at frequent intervals and the chances of successfully adopting the animal were slim, so we called the local council and a ranger came. We trapped the animal with his hunger and he was taken away--most probably to be put down.

Each time I walk in our yard and see his favorite places empty, I feel guilty.

Abandoning animals is an offence in Australia. Just at this moment, I'd like to see it punished with the death penalty. (Nonsense, of course, but I feel bad.)