Hi Carla-
When you get to speak with your surgeon, please make sure to mention your fears. Tell him/her that it is probably beyond the norm. He may have a nurse or PA on his staff who deals with per-surgery jitters, and has had lots of experience dealing with similar fears. And they may be able to do things a little differently in the ICU to help you have an easier time. The breathing tube is very, very necessary after surgery. Without it you wouldn't be able to breathe. Anesthesia still in your system, and pain meds, which you would definitely want to have, can depress your respiratory system. The breathing tube stays in until the constant monitoring shows you will be able to breathe on your own. It is to keep you safe when you are not able to do things on your own. If someone can explain the very scientific aspects of the breathing tube, step by step, it will help you to understand how the gizmo works to your benefit. Fears of the unknown are something all of us have.
Please do read the posts from ccrawford. They will help you a lot. You can see where his fears evolved from extreme to acceptance with a little anxiety, and then after surgery, telling all that it wasn't as bad as he had imagined.
I believe that in his posts, there is a detailed explanation of the breathing tube. It's a good description.