I think the fertilizer overdose would be much more likely to have hurt the plant than the additional water.
Pamela, I believe the "2 tablespoons per gallon" is for plants growing in the ground; best to use a much weaker solution for house plants. I'm not sure whether there is any hope for the plant at this point, but my inclination would be to remove as much of the soil as possible and re-pot with a good potting mix. Kind of a "what is there to lose" thing...
