I am really confused and don't know what to do. I was with my ex on and off for approximatly 6 years, and we moved in together in August 08'. He started sharing some sexual fantasies with me shortly after. He was really into roll playing (me being his young daughter). At first I didn't think it was a big deal as lots of men fantsize about incest. After a while he wanted to do it every night, and would say things like "you can't tell anyone or I'll get in trouble". That escalated into him openly looking at "teen porn" and incest porn. I would find searches on the computer for "young vergin sex" etc. He became more comfortable with sharing this fantasy with me, and started talking about having our own kids and teaching them sexually when they were young. He would even on occasion say "i'm serious about this" or "i'm not just playing".
I left him a month ago because he was also verbally abusive to me when things didn't go his way. The thing that worries me here is that I'm unsure if he would ever turn these fantasies into reality as he does not have me around anymore to do this with. He told me that he had never told anyone about them except me, as he never felt comfortable enough with anyone else. He has a 6 year old daughter from another woman, and I am also pregnant with his child. I don't plan on getting back with him, but I am worried about how serious these fantasies actually are. I am having a hard time with this as it is such a serious issue, and there is no going back if I tell someone. This could ruin his life, and put me in a lot of danger. On the other hand, I feel that if I don't tell someone, his daughter, our child, and other children could be in danger if fantsy turns to reality.
I just need some advice on how to deal with this. As I said, this could be detrimental to him, his daughter, and even dangerous for me; but what if he is actually dangerous to the children??? What do I do????