This was a tough one for me too, considering I went NC right off the bat with my WAS.
I think confidence is something that is sensed by people. You can't go around telling people you are confident.
The trick is to "act as if" you are going to be ok without your wife if she ultimately decides this is what she wants. You need to have a mysterious aura about you. Like you are excited about the next chapter in your life (without overdoing it and coming across as fake).
Have you read the DR book? Have you read Sandi's 37 rules?
