I feel CERTAIN that a physical affair is worse because people often get shot engaging in same when caught by the husband/partner.  Also, they can bring home a venereal disease, which is a dead giveaway that they are cheating.  These things don't happen when someone engages in an emotional affair over the internet, cell phone, at the office, etc. without ever having sex with that person.  These seem to be relatively harmless, in my opinion, and can be good for a relationship, because if the people engaging in the "emotional affairs" get turned on talking to one another, then perhaps they go home to their spouses and take out their sexual energy on them.  (Unbeknownst to the spouse, they are the unwitting recipients of a good time.)  I could be wrong, but that's my opinion.