Laura, My father also had surgery, although not as extensive as your fathers. It is a difficult thing to see and go though on both sides. I too spent a lot of time in the hallway sheding tears because I didn't want him to see me cry. Suctioning out the breathing tube was the most difficult thing for me. I would hold his hand and shut my eyes. Fortunately Dad doesn't remember most of the three days immediately following surgery.
When I look back now, I see that I was a lot stronger than I thought I was. It's ok to cry - it doesn't mean that you are weak, it just means that you care. Hang in there. It's going to get better.
Joy