I lost my beloved Toby after 17 years and I know how very much it hurts. I couldn't believe that I could hurt that much, even though he was old and it was not unexpected. That was 9 years ago and I think of him often, still.
All I can offer is my empathy and the comfort of you not having to go through this alone. Your cat was very loved, he knew that you loved him and he was safe and fed and warm...all blessings for any cat.
Hugs from my heart to yours.