There was a large delivery van parked on a double yellow line blocking the lane of traffic. I had to reverse from beside the van to behind it to let another car pass me on my right hand side. While I was straightening up I hit the tailgate of the van not knowing that the tailgate was there because I couldn't see it. This damaged my car but the van is fine. Am I solely responsible for paying for the damage to my car? The van should not have been parked on a double yellow line in the first instance blocking a lane of traffic with its tailgate down