This isnt very good news at all. Hope it gets sorted out.
But, looking at it from the other guys point of view, i know i wouldnt be happy if a car i had just bought wasnt all that it first seemed. Im not implying that i think that of this car, im just pointing out that it can happen and obviously any of us would be wanting our money back aswell.
The guy shouldnt have made threats and should be trying to prove that the car has accident history as he seems to think it does.
Private sale tho, sold as seen.
Anyway as i said before i hope it all gets sorted