Imagine how you would feel if she hurt someone with your car. Then realize that if she hit someone then panicked and left the scene, it would be YOU they would look for. I'm sorry, but she should NEVER be allowed to drive your car.
You should free yourself completely from her dependency. Ask her to find other transportation, you are stressing yourself out over something that is her responsibility.
You sound like a lovely person. Hugs for you!
