Traffic Accident in a parking lot!!!?

OK. My mom and I where beginning to pull out of our local gas station's parking lot when all of a sudden a blazer who was going over the speed limit turns into the parking lot and a small accident between my moms vehicle and the blazer occurs. We hadn't even pulled up enough to pull into the highway when the blazer shot in front of us and we both collided. They gave us a ticket I do not know about the other driver but we went to court and they judge through the failure to excess due care ticket out of court. At the time my moms insurance was expired because she had forgot to reinforce it but this other person's insurance company is saying that we owe them 3000 for damages done to the other persons vehicle. It didn't leave but a minor dent on the door! But anyways, we where not proven guitly in court of causing the accident and I was just wanting to know if there was any way that the insurance comany could make us pay it because it was as much as the blazers fault as it was ours. Any advice appreciated. Serious answers only! My mother and I are very safe drivers we have never had a traffic ticket before this one. I just want advice because that seems like a lot of money for a dent on a blazer. We also live in tennesse if this helps and like i say the accident didnt even happen on the highway the blazer whipped in front of us while we where pulling away from the gas pumps.