Scratched bumper after accident?

yesterday i was parking my car and i tought that i didnt have enough sspace to park . luckly for me ($^&^&) there was a lady in the car parked in fron t of me so i went there annd asked if she could move a little so i can fit .. she ignored me twice!!!! so i went back to my car and i hit her car by accident no her car has a little scratch like an inch long .. she called the cops and everything but after talking we agreed to do nothing we didnt ever fill out a report . but im worried that she might fill out a claim with the insurance ..can she do that after agreeing to do nothing ?? hou much will it cost . ?? her car was a 2010 toyota