I understand how scary this is! I have bad reactions to anesthesia, and a really hard time waking after. I recently had my wisdom teeth out and was petrified. I told my doctor my fears (over and over- he was probably sick of it!) and they said they'd monitor me very closely.
I still got very sick and even threw up while under (which is not good). I also think because I always have a hard time waking up they didn't give me enough, and I woke up during surgery as well. It was awful.
Sorry!!! I'm supposed to be giving you reassurance.
I hope everything goes well. Is it going to be in a hospital setting?