I think everyone has a sleepless nights before, but soon you will have had surgery and on the road to recovery, I have had both knees now replaced, the left in 2019 and my right in 2021 and I can say it was my best decision ever.
The first week or so is pretty tough but it will get easier each day, make sure you have a bunch of good movies to watch, this will distract you and keep things close by, large pockets are a blessing.
Good luck with your surgery today x