Sorry to hear man. Its tough to go through. I had to put down my black persian 2 years ago due to cancer. Held her in my arms at the Vet till she passed away.
What helped me through it was to get another kitty. I got baby bear...another black persian 3 weeks after Precious was put down. Now the good times remain in my mind and know that she is in a better place.
Again sorry to hear
