The viva isn’t the top of the mountain. It’s not the hardest challenge, the last thing to do or the most difficult conversation. The stakes aren’t raised to such a height that you are risking everything when you talk to your examiners.
Prepare for the viva, rehearse, remember what you’ve done to get this far.
You’re not at the top of the mountain: you’re already working your way down the other side. Tread carefully, but with confidence. You’ve done the work and are more than capable of doing what you still need to do.