I am scared and worried...help?

My 3 year old daughter is going to have surgery to remove an lymphnode behing her left ear. The doctors say that it isn't a big deal and that she could live with the lymphnode and it might heal on its own. But it is bugging her and has been there for months so they suggest we have it removed. And I decided that we should do the surgery...but now i am freaking out. The doctors told me it is quick and simple and i dont need to worry but I CANT STOP FREAKING! I mean she is my little girl...I keep imagining something will go horribly wrong. How can I calm down? I don't want her to see i am scared...help?