I'll share my view of the scene. Although you two are married, and may be intimates, I think you violated her privacy being so curios about her personal messages. You found out something that you didn't like - She's having some hot messages with this fellow here. They work together. Your partner is human... she has her desires and needs. If she felt like it and had sex with the fella, it doesn't mean that she doesn't love you, or that she no longer care about you. It doesn't mean she acted with intentions of hurting your feelings. It doesn't mean she doesn't respect you. Marriage can be fucking suffocating sometimes. I don't believe that repressing libido and restricting love-giving can be a good thing for human beings. Be her friend and show yourself open to new sexual experiencing. New ways to please her. New ways to satisfy your bones. If you love her by heart, and if it is true that she loves you too, get over it! Don't be with the attitude of the respectable man seeking for justice/revenge or whatever... This is your relationship with the mother of your child, not some court case, or a math problem. One thing is true - she was not open with you about her supposed will to make love with her work-mate. I ask myself if she should have been... Maybe I wouldn't, in her position. These desires are in a personal intimate realm to me. I would do it, or I wouldn't do it. But I certainly wouldn't going to tell anyone about it. It's understandable, she has a son with you. You live together. Maybe she doesn't want to tear it all apart. But talk to her Call her for a sincere conversation and tell her how you feel. It's okay if it makes you cry, I know, this fucking hurts one's feelings. Please, first apologize for having read those messages, it was not nice of yours. You must respect her space. Listen to what she has to say about it. Know when to take a break. I understand this can me emotionally exhausting. You love her. Even though you may be hurt, try to be tender still. Open this relationship up! Love!