The lady was on the left because she was eyeing on a parking space on the right and about to drive into it. It is impossible for a car to turn right to enter a parking space in such a narrow space without being on the left hand side of of the driveway between the spaces. I think what really happened was very simple. She forgot that you were behind her backing up from your space at the time she got the brilliant idea of using the newly freed up space closer to all of you requiring her to back up. It was a silly mistake she was probably embarrassed to admit to. Being careful not to tread on her ego while being firm about the facts will help in resolving this with minimum hassle. Anyone is capable of making such mistakes. The fact that a car passing by may have right of way does not mean that a car partly backed out of a parking space is allowed to be rammed into.