Did I just kill my fish of shock?

Yes, unfortunately the water change probably did kill your fish. Always either age your water or use a water conditioner. I use "Prime." Also, goldfish prefer cold water. Where I live the tap water is almost 85 degrees at it's coldest, so if I were to change the majority of the water and replace it with water from the tap, I would have to do it very gradually and add ice to keep the temp the same. They can and will go into shock if the temperature fluctuates too much. So sorry about your fishy, I hope the others are ok.