I'd venture to guess that the toilet tanks were full or close to full. Maybe because the restrooms weren't serviced in Barcelona. Maybe because the passengers/crew, um, filled them up.

Being low on fuel: I'm sure Continental had the fuel tanks full before the flight took off. You know how your gas mileage can vary in your car? I'd bet jet fuel mileage varies, too. Windspeed, air speed, weight, extra-long takeoff could all factor in.

For all we know, there was enough fuel to get to Newark, but only if the plane could land immediately. Kind of like the car running on fumes. You might take the chance that you'd reach your destination with your gas tank registering close to "E".

Continental could not take such a chance with an airplane full of people. Weather delays, closed runways, plenty of other reasons the plane might have to circle for a while before landing. There aren't many places to refuel between Barcelona and Newark(probably none!). Halifax was the closest "gas station" the plane could get to.

Your failure to wake your seatmate is not Continental's fault.

You should continue your loyalty to Continental because they delivered you safely to your destination. Apparently on time and with all of your luggage.