This is a question I struggle with too. How do you re-build trust? Well, it's not going to comeback right away, but I think it's probably a lot like how you built trust in the first place. One thing that comes to mind in consistency.
I think the first thing to do is recognizes your role in why she sought the OM. By addressing that you'll greatly decrease the likelihood that she will do that again.
But you have to make a decisions and yes I believe it is a conscious to forgive her, move past what happened and in time the trust will build back up. But you have to make that choice.
Do you have an IC? I talk to mine about it and he said you have to work through it and there is a process.
There are ways to assist rebuilding the trust. Unless your W is a complete moron, she knows what she did damaged your trust and was betrayal. I'm certain she wants you to trust her again. Just like she wants to trust that he changes you made aren't just to win her back. You can't harp on it nor can you attack her when you bring it up.
I also think you need to be honest with yourself. It was more than lying. Heck, I bet your W lies to all the time about small things and you don't light into her. What she did lie about matters, you know that.
If you aren't in MC, this may be a good reason to start. Sometimes working with a neutral third party can help.
I do not think pretending nothing happened and moving on is wise.
Patience is bitter, but its fruit is sweet. --Jean Jacques Rousseau.