You are such a sweet person for taking the sick and doing what is humane. I trust that the kitties that did not make it beyond their vet visit we spared the pain of having a slow and awful departure. You are doing the best you can. I don't think I could do it. You and Aly and Jen....and all those others who take in strays, ferals, fosters etc. are all angels.
Relax, have a glass of wine and remember that you are actually doing these furry creatures a favor by not letting them suffer.