She’s already moved on.

My dude. You just got rocked, and it's going to take you a long time to recover. Do your future self, and kids a favor, get therapy, and lawyer up. This is going to be one of the biggest decisions of your life, and not caring is not an option. Have the lawyer give you your options, reach out to someone close to lean on. If you can't do it for yourself, do it for your kids. There's no shame in this... She fucked up... She hurt you...

Also, collect evidence. Take time off of work if you can... You got this.

Weirdly enough, this isn't your fault. You had suspicions, and you acted on them. In a healthy relationship, spouses should have no issues sharing their communications with others to their SO. Look, it took me a long time to get over this simple truth, but you can't control how other people feel about you, all you can do is react to the information you're given. She made her choices, and there wasn't anything you could have done to prevent it. The only person who had control over this was her.