I'm going to tell my wife I want a divorce when I don't
Why would you say you want divorce when you don't?
I found out about her double life and it disgusted me but I still love her.
It's understandable that you're hurt by your wife's lies. But you shouldn't reply to lies with lies. Two wrongs don't make a right.
Can't I still be making the divorce demand? That should make her feel bad.
No, because then she will take it seriously and divorce for real.