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.