Sorry to hear this
I took our cat (which I picked out of the litter at 4 years old) to the vets to be put to sleep when I was about 20....and I cried like a little baby.
Cats become so much like part of the family and I so miss having the little shit around. He was such a playful boy. Thankfully we do have another kitty who is my little princess and is spoiled rotten and has the run of the house