He's obviously lashing out because deep down he knows he's at fault for not looking where he was going.
I was in a similar prang at a roundabout some years ago - my car had a problem with the electrics and cut out as I set off, and the car behind rear-ended me. He started trying to crack on that it was my fault, then his wife got out from the back of the car and asked if he wanted to name her as a witness! I said 'No, luv, you go on a different part of the form'.
After some pathetic point-scoring and trying to intimidate me, he gave me his insurance details. It gave me great pleasure to inform him that I used to work for his insurer (I didn't mention that I was a typist in one of the life insurance/pension departments) as it really took the wind out of his sails - game, set and match to me. I informed my insurer in the morning, who told me that the bump quite obviously wasn't my fault, and my car was fixed and paid for, courtesy of his insurer, within six weeks.
