We all have to believe it, unfortunately.. people are capable of all sorts of underhanded, manipulative mind games. I was once pretty naive as well.

I didn't experience quite this situation, but I certainly experienced a situation with someone that presented a completely distorted narrative of their life to me. They were sleeping with multiple people, lying to all of them, and basically living different lives online and off. They even had unprotected sex with many different people in a short space of time (some of whom were met online or dating sites, others not) - potentially exposing all of them to any number of STIs. At the time I was completely shocked and so disturbed when I found out. I really didn't think that I would ever get wrapped up in that kind of thing.

I'm sorry this happened to you, but at least it's over and you didn't end up meeting someone like this in person and have them carry on the double life/charade afterwards.