Every once in a while I see him in that same singles chat room. I'm going to log into the chat room with a different screen name and start up with him to see how he responds. The Internet can be a great tool for finding a relationship and an equally great tool through which to lose it. Having benefited from one feature, it appears that you are poised to take advantage of the other. This man might be drawn to the singles chat room out of habit or because it is a comfortable place in which to socialize and connect with friends.
People like to visit their old haunts and even married folk occasionally read the personals.
However, it's also possible that, while he is only seeing you at this point, he may not be ready for an exclusive relationship and is keeping his options open. For whatever reason you also found yourself drawn to the same singles chat room. Perhaps it was only to make sure he wasn't there. Unfortunately, your fears were realized and there he was. In your attempt to make sense of this bit of knowledge, you are in danger of losing the relationship.