how can i say it in a friendly way...

well, i think you should tell her straight away

I would write her a note telling her how you truly feel. if that doesn't work then try sitting down and talking with her face to face and explain how you feel.

Is it possible for you to give us example how she annoys you? So, I can analyze the best way to speak to her. But actually, the only good way is to listen to her without giving any response, at least only say "yes" or "no" because that way she will be bored or will ask you to explain why you only answer her with short reply, and just tell her you understand enough, and she does not need to repeat because you've known it. Somday she will run out of amunition and stop talking.