I agree that you shouldn't feel guilty about taking care of your old friend. To me, some things are just so much more important than a job. Missing moments like that with your baby would stay with you forever, a couple of days at a job really doesn't mean anything in the end, does it?
I just lost my 17-year-old baby this June. I, however, feel so unbelievably guilty that I neglected him too much in this past year. I was going through such a hard time, and I took for granted the fact that he's always there. I just didn't give him all of the attention he deserved. I sat at the vet's office with him for nearly 3 hours every day just holding him and grooming him and crying before I had to let him go. They would even let me come in on the weekend when they were closed. I still dream about him at least 3 times a week. The other night I was dreaming that he was "haunting" me, but I was so happy that I knew he was there I cried!
You have the right to feel however you want to feel about your cat. Don't listen to anybody else.
Take care of yourself during this time,
Sara