Melissa, I am so sorry to hear of your sad news. But please do not blame yourself, you gave him the best life, a loved and cared for one. And you cannot think that you had anything to do with him passing on. It is one of those mysteries of life, the things that make you wonder, what could I have done, could I have done more?
But it's only natural you will blame yourself because of the grief you are feeling at losing a beloved cat.
It will pass, and you will see you did all you could for Ying.
He is now at the rainbow bridge with all the other cats, and he will make sure you get the message that he does not blame you,and that he loves you.

Hugs from myself and Jack & Sunny x