Poor Little Loopot

I got home from vacation and found my cat very dehyrated. It is my fault and I feel so guilty and negligent. The cat has diabetes and is fairly old. I had a bag of the right food and a bag of the wrong food at home. I should have thrown away the bag of wrong food. The pet sitter chose the wrong bag and gave it to him, and he threw up all weekend. Which is very bad for cats, especially when they are old and diabetic. I am giving him pedialyte tonight and am taking him to the vet tomorrow. But I feel like a bad mom.