Sorry, but that plant looks like a goner. Unless the water with fertilizer was a very strong mixture, i doubt that the fact it had fertilizer in it did any harm. It's more likely that the spraying accumulated water where the leaves met, and caused a rot; probably bacterial.
Lou Sneary's like to mounted or grown in a basket so it's roots can dry out rapidly after watering, like vandas. Moss is definitely out for them.
It won't spread, but I'd suggest you stop spraying everything. Spraying is always dangerous, in my opinion, and can cause rot in your other orchids.