"WTF is it with people thinking that just because they are getting married nothing else in the whole universe matters?"
This shit here. It's all here, on this thread. It's her big daaaay and that means nothing else matters.
This whole stuff of Big Daaay comes before all, is part and parcel of the madness of the wedding industry. The madness on this thread is fuelling it, people, it's creating Bridezillas It probably is unfair to characterise the daughter as a common or garden Bridezilla, clearly there are issues there which it will probably take her a good few more years to sort out, but this insistence that the Big Day is the most important event that can ever happen to anyone and that therefore the mother needs to be there, is exactly what fuels the madness.
The reason this young woman was able to make such a destructive, insensitive and downright selfish decision, is because she is surrounded by messages like the ones on this thread - that it's her Big Daaaay and everyone else in the world, no matter what else is going on in their lives, has to fall in with her desires. And if they don't, then she's justified in cutting them out of her life forever, because her abusive demand that an abuse victim come and pretend to play happy families with her abuser, is perfectly acceptable because Big Daaaaay.
FFS Mumsnet you're better than this. Stop fuelling wedding-industry insanity. This thread is a sort of microcosmic example of the sheer crap around it. One of the reasons that brides feel so disproportionately outraged when things don't go their way, is precisely because of the clamour they hear from threads like this, that they have the right to feel epically pissed off. Stop telling them they do - the DD wouldn't be so hurt and upset and outraged by the idea of her Mum not going to her wedding, if she wasn't getting messages from different places, telling her that hurt, upset and outrage is the minimum response necessary, to any disruption of your plans on your Big Day.
FGS don't let Mumsnet be one of those places. Have some fucking proportion and dignity and stop being cheerleaders for the wedding industry.