One of the best pieces of advice I have ever gotten, actually from The Concientious Marine Aquarist... take your food with you when you leave for vacation if someone will be sitting your tank. If you dont want to bring it with you, throw it away. It is better for your fish not to receive any food, even if it is for a couple weeks, than to be overfed or have something like this happen. People kill with random acts of kindness.
Sorry to hear that this happened to you. Hopefully you will be able to recover.