Are they your friend or the wives/girlfriends of your fiancé's friends? The reason I ask is that if they are not your friends, then they really aren't beholden to attending a party arranged by someone one step removed. Their attendance isn't needed and, to be frank, your description of their social mechanic suggests that should not be a big deal.

The sensible advice is to move on, ignore them, and cease trying to be friends with them.

My less sensible side is all for drawing the line in the sand and dis-inviting them from the wedding. To be honest, they sound like a shower of bastards that will turn your wedding into their social gathering.