WannaBe I think that is an interesting point. We seem to get so fixated with the idea that either the first (ex) wife is a psycho bitch loon or the second (current, maybe OW) is indeed the psycho bitch loon, that it in some way has to be one or the other.
We here so many stories on here, in RL, from our own experiences etc about the second wife / OW / stepmum etc being a husband stealing bitch, evil step mum ('i'm not having that women near my dc' mentality), ''hope he leaves her and screws her over', judgemental accusations blah blah.
And yet so many first wife rants - 'my dp's ex is a psycho', bitter and twisted first wife, money grabbing ex, screwing the kids over etc. as well.
The reality is most people are just normal! First / second wife, OW or not. Most people just deal with stuff, get on with it and live their lives like a normal rational human being. Obviously there are some immature, deranged, bitter, revengeful, psychotic people out there, who may or may not be a first / second wife (or OW).
It seems like society (at least Mumsnet) need to focus on finding the 'baddy' when a relationship breaks down.