My parents went on vacation and my father asked me to answer email from a client on his behalf, because he was cut off from the Internet. While searching for the relevant emails, I came across a couple of messages that had subject lines such as, “Hi Dad, I love you.” These were not from my siblings. I dug through his inbox and found several messages from what sounded like a teenage girl calling my father “Dad.” I also found a few angry emails from the same address that I’m assuming were from the girl’s mother. My parents have been married for almost 40 years, and I had always assumed they were happy. I don’t know whether to tell my siblings—we’re all adults—about this, confront my father, or reveal this to my mom. My mother is completely dependent on my father financially and emotionally. I am going to be married soon and this makes me lose all faith in marriage and relationships. My father was my hero both as a husband and father, and if he is this sleazy I am not sure how my fiance and I stand a chance. Do my siblings have a right to know what going on? What is the path of least harm?