Sorry to hear this, TC/OP. I had a cat when I was 19 that my mom had gotten I believe from a shelter. The cat was a small kitten, he died a week and a half after we got him.
Whats funny is how he died, he moved slowly.. every now and then, I had to look up on the internet what to do when kittens were sick. I looked frantically and checked moments later, the cat stopped moving completely--he died. Was very hard for me to deal with primarily cuz I felt responsible, but its tough to lose a pet either way.