Need advice on parking lot accident! Thanks!

A week ago I scratched a rear bumper of a car at my office parking lot. It was a minor scratch and was a brand new car with temperary plate. I felt bad so I left on note saying " Sorry I scratched your car and my phone number is xxx".

Today I got message from that woman saying she just got estimate from her dealer and needed to talk to me. I am willing to pay $100 to settle it but if she insists to have it fixed which will cost much more, should I just let my insurance company handle it? Will that increase my insurance rate? Thanks!