First, realize that you have a life of your own. You can heal and thrive, even after being betrayed.
Second, start thinking about what you need and want. You been traumatized, which has long term effects, and shocked, which has shorter-term effects. If you find things in the Healing Library that make sense but are not part of your thinking yet, you can simply change your thinking and request you W to change hers, too.
Third, rebuilding trust takes a long time, because you need to see lots of trust-worthy behavior before you can honestly give trust again. Your W can start rebuilding trust right now by being transparent, honest, working on her issues, and supporting you emotionally.
As you read SI posts, you'll come to see that she cheated because of her issues, not because of anything you did or did not do - you're just collateral damage. Even though the cheating is on her, though, if she does what she needs to do to heal, she can become a great partner.
But you have to heal, too. You're probably overwhelmed with pain right now. Accepting that pain and feeling it is a way to heal - IMO, the only way to heal, but you have to find your own way through this.
And always keep in mind the general SI approach - take what makes sense to you, and ignore the rest.
Also, lots of people start out thinking one way will work for them but then find another way works better. If tat happens to you, remember you can change your approach whenever it seems like a good idea to do so.