Welcome to HealingWell and the A & P Forum. I am so sorry to hear you are having so much fear re your surgery and not waking up.
It does sound to me like you are anticipating the worse case scenario..............try to visualize yourself doing great and waking up to the wonder of knowing the surgery is all over and you are on the mend.
Kick all that anxiety and the "what ifs" you are going through to the curb and stay in the moment.
Really concentrate on not trying to guess what the future holds but believe that it will be good for you.
Again a warm welcome