It's possible that the relay was starting to fail, which was why you had 12.5 volts going to it & only 10-11 at pump & now the relay has failed completely. It or the harness must be shorted to ground if the wires are getting hot(heavy current draw). I wouldn't be turning ignition on again until you find out what is shorted, as you'll be causing more damage or something catching on fire, although the fuse's/breakers at front should open before that happens. Maybe the pump is seized or shorted internally & that was drawing the voltage down? Sounds like the relay has failed now, but thats the result of other issues, not the original problem. You'll need to find & fix that before replacing the relay or you'll just burn it up too.