When I had my surgery, it was a first for me. I hadn't been in the hospital overnight since I was 8, and here I was at 50 having "anywhere from 12 to 14 hours" of surgery.
It turned out to be 17 hours. As for being afraid...terrified almost to the point of being paralyed with fear was an accurate description.
As Nelie said, suddenly you're asleep, and waking up with it all behind you is a relief. The pain management issue is one everyone fears, and it's really effectively managed these days.
If you have pain, speak up; they WILL address it. The days of pain medications only every 3 or 4 hours is long gone.
Much luck, you'll do fine
Wayne