I'm so very sorry that you lost your your kitty. It is heartbreaking but you did the right thing. I lost my cat Rudy about a year and a half ago. He suddenly developed feline asthma at the age of 10. we thought it was under control but he had a bad attack and even though the vet is literally 2-3 minutes away, it was too late. It's devastating. I cried for 2 weeks. It was 3 months before I could even look at his pictures again. I still cry sometimes, and I still think I hear his meow at times or catch of glimpse of him lying in his favorite spot, but it does get better as time passes.
My thoughts and prayers are with you.