You gave your cat a life that many are not lucky enough to have. Think about that. He had a home. He had love. Food and water.
Don't think about what you should or should not have done. You are only human. I can tell you this, your kitty died happy. He had a family that loved him. He knows you love him.
If only every cat was that lucky.
Be strong. You'll meet again eventually and you'll see he loves you like family.