I am sorry to hear that that poor Cat is so ill.
I had three Cats who had to be PTS by My Vet, and thankfully as they were Strays , he only charged me for their burail and the needle that made them Angels.
They were laid to rest by the wishing well where all the Angels go so they can wish for a better future and as Awesome Angels they are free at last from pain , cold and hunger!!!
God Bless You for caring when so many would not.
You will be rewarded with so much love.
One Fine Day