My question involves an injury that occurred in the state of: California

A driver started tailgating me when I was on the left lane. The road was clear so I don't know why he didn't move to the right lane. He started honking at me and yelling obscenities. He moved to the right lane and started driving along side me to yell obscenities. He then changed lanes again, but now he was in front of me and he started driving really slow. I decided to move to the right lane to avoid any confrontation. While I was in the right lane he tried to change lane to the right lane and ended up hitting my car with his front right bumper. He hit my car on the Left and side front bumper. He gave me an expired insurance card, which i did not notice until after. I made a statement with my insurance, but never made a statement with his insurance. I got a letter today from his insurance stating that I was 100% responsible because I "was changing lanes." Do you find this as a reasonable decision by his insurance?