Sorry to hear about your situation. From what I can gather, it appears that she hit the rear of your car while you were waiting at the gate of your apartment complex. If this is true, it's going to be quite difficult for her to make the case that you backed into her. That said, with no witnesses or police report to go from, you will likely need to get your insurance company involved. Even if you are not eager to get them involved, they can represent you when dealing with the other driver's insurance company. They can work on your behalf to assign fault
and determine which party must pay out. Good luck. Don't hesitate to ask
if you have any questions.