Hi, You have a beautiful plant there.
If you really did over water your plant, it will be best to cut off the spike and save the plant's energy. It will grow a new spike once it is healthy.
Don't worry too much because it shouldn't be too hard to save because you say that it has 1/3 of its roots and four leaves. That's should be a easy save because there is plently of plant left and phals are vigorous plants. Repot the plant in a media comfortable with you and try not to overwater, it will grow new roots soon. The bottom most leaves normally do fall off eventually, but they may be supplying your blooms with the nutrients so they wilted.
Is that plant permantly growing next to the bathtub? It wouldn't be getting enough light if this is the case and over watering may not be your only issue. I certainly wish I could grow one this way, it looks great in over there, but they really should not be father than a foot from a window, because light diminishes dramatically indoors.
How often were you watering? What type of media is it growing in? Your plant doesn't look bad from this picture