Ricey,
You HAVE to inform your insurance, even if it's not your fault and your not intending to claim from them.
The accident will be on your history, no matter which insurance you claim from. It just goes down as a non fault accident, but still incurs a loading. Most insurers ask if you have had any accidents in the last 5 years whether it was your fault or not.
You really need to inform your insurance, they fix your car and then chase her insurance for the cash, this is how they make their money. I crashed our Alfa recently and admitted liability but the other guy still went through his own insurance to get his courtesy car and get his car fixed and they are now recouping the money from our insurance.