@The Pentacle Queen,
Don't beat yourself too hard!
You probably never had any animals to take care of, right?
At least you start the right way with a fish that needs very little attention
and even then it can happen. Very few people haven't found the pet goldfish floating at the surface when starting out. It does happen!!
To ease your conscience you could volunteer at the local animal shelter -
that would be a good deed and take your mind of yourself a bit.