My Dad Worked With Satan

19 years ago, my mother left my father after finding out she was pregnant with me. She never told me until a few days ago, the only reason being was she found out he went missing. Out of the blue, he just vanished. Me and my mother went to his apartment, I was hoping to find some answers to some questions I had, my mother though. I'm sure she felt guilty after leaving him like she did, a little less after she saw who answered his door though. His girlfriend. She seemed... less worried about the whole thing like my mother had been. My dad's girlfriend gave me a few journals he had written, she said it would help explain everything. I expected some manifesto or some kind of autobiography, but this? This was something I'd never expect..