Chris, the only way I can see water having such a drastic effect on a
VFT is if you used hard water or water with chemicals or fertilizers in
it, they love to be kept wet especially in the growing season. Keep the
pot sitting in about an inch of distilled, reverse osmosis, or clean
rainwater constantly, you don't have to water them from the top with
this method and you won't disturb the traps.
You say the change happened at once? That pretty much rules out pests, the
weakness would be more gradual. Check for them though just in case.
Is your plant covered with one of those plastic tops? They use them in
nurseries to keep the moisture high so the plant will survive the long
journeys to the stores without drying out, you don't need them with a
plant you are watering, regular room humidity is fine. In fact, if your
plant is in a sunny window and has one of those covers over it I think I
know what might have happened, when the sun hits that plastic the
container heats up dramatically, you might have boiled your poor plant!
Give it plenty of light, keep it sitting in water, and remove any
plastic cover, hopefully it will make it.
Regards,
Demetrios