I would not drive the car.. at all.
Call carmax and tell them you have to have the car towed. Im not sure how good their service department would be about repairing a car like ours, I would see if they would let you take it to mercedes or chrysler.

Your water pump has either failed and the bearing let go, or its very near to death. DO NOT DRIVE IT, its not worth the damage it would cause if the pump shaft failed