Who is at fault if I was backed into a parking spot?

My boyfriend and I were in a car and I looked right left, then right again and pulled out. Keep in mind that I was already backed in so when I turned left, I was in drive already. After looking both ways, the car that had already passed decided to reverse and couldn't stop fast enough so she ended up hitting me. The police came and she told them she passed a parking spot and decided to back up without looking. He said the cause of the accident was improper backing but he was going to take measurements of the parking lot and write p the report. He told him to file a claim but her insurance hasn't contacted my family or me yet.