I think writing things out really helps put feelings and thoughts into perspective. Whether that be here, or in a journal, blog, email, etc...
If the other guy has a girl that he is talking to or another girlfriend, is he being honest with her that he is also interested in seeing your wife?? I can tell you as a wife of a coupe who was in a V, it is hard to watch the end of a relationship because there is dishonesty involved in the other side of the V.
Also, I think it is important that you and he talk, and have an open line of communication.