I've been in a committed relationship with a man for 2 years. A few days ago, I casually happened to glance at his email while I was sitting next to him when I saw an email with the subject "Sweet call with a little girl" with 36 messages in the email thread. I immediately asked him what that was all about. He admitted to keeping in touch with a Vietnamese girl he dated while he was traveling through Vietnam (my boyfriend is Caucasian) but he said it was strictly platonic. They stopped seeing each other because my bf had to come back to the states for work, but have kept in touch for the past 3 years (2 of which we have been together). They exchange emails monthly. I was extremely uncomfortable seeing/hearing about this, so I asked him if I could read the messages. He reluctantly agreed. In the beginning, the messages were romantic, because my bf was still single at the time. They increasingly became more platonic from his end when we started dating. The Vietnamese girl knew about me as my bf brought me up a few times. However, it was very apparent she had somewhat strong feelings for him. Although my bf was only casually dating her, she compared their "story" to a movie she saw where 2 lovers have to part ways for work reasons but meet up after 5 years and still care about each other, but both may be leading their separate lives. She would also ask him deep questions about his life and share very personal information about hers. She talked about her past pain and would repeatedly tell my bf how his presence "changed her life." I then got to an email where they were talking about meeting up for lunch because she was in town. My bf never told me about it because he was afraid I'd say no, and met up with her for lunch behind my back (we were together 1.5 years at this time). I only found out while going through the emails. The last email she wrote to him was a long rant about how she thinks she'll never be loved again. The email ended with "I know how you would look at me if you were looking into my eyes right now..." I find this to be extremely disrespectful to me and our relationship. When I asked my bf to cut off contact with her, he said he needed time to "process it" because he really cares about her as a friend. He didn't think it was fair for me ask that of him. He finally caved and told her they couldn't talk anymore. Am I being unreasonable or is my reaction completely valid? Thanks in advance, everyone, for your advice!