A car in front of me( a few car lengths) suddenly made a wide sweeping right turn, almost a u turn. I slammed on my brakes, and my front left side hit his passenger back door. He was sited for unsafe lane maneuver and I was sited for 30 in a 25. His insurance co. is saying that I was at fault because it was a rear end accident. I sent them photos when the cars were still in position. How can I be at fault.