Oh no Allie, I'm so sorry to hear that. What a trooper he has been, and you too. No matter what happens from now on, Toby has been a very lucky kitty to have you as his person, and he's had a really good life.
Toby is one of my favorite cats on this whole forum. This news has come as a shock to me, and I am deeply saddened. But I know that you gave Toby more happiness than any cat could ever hope to have, and even when the time comes, he will be with you in spirit forever.