Well, if you are not happy with her you are perfectly entitled to leave at any time. I mean, she is paid for a service after all... You can always send something written, call her office/secretary, leave a voicemail or (if feasible) stop coming altogether.

From the description you give, it doesn't seem you are close anyway and therefore seems unlikely that you would hurt her. Ultimately, I can only advise you to do what is best for you.