Not just Irish, Northern Irish. I knew it. I've lived this, OP. Not my parents, but an aunt who had 'head of the family' pretentions and was an unholy pain in the arse about everything wedding related for me. We don't speak any more, I bear the deprivation tolerably.
OP, How many Irish mothers does it take to change a lightbulb?
"That's ok, don't bother yourself, [sniff], you go out and enjoy yourself, I'll just sit here in the dark. By myself. Alone. Cold, alone and in the dark..."
(Disclaimer: I am Irish, I'm allowed to tell that joke)
Something seems to snap in the minds of certain people here when there's a wedding. It's a hideous combination of 'what will people think', various obligations both actual and imagined, a chance to run mad with the planning they didn't get to do because their parents ran rough shod over them and often, and most potently, a chance to make a huge fuss and really rub it in the face of so and so from church whose daughter married a consultant and had a huge doo in The Culloden.
You have my sympathy, and my respect because you're doing brilliantly and fighting your corner against a wall of guilt and manipulation. It feels horrible, I know, but better the large drama now than the steady drip of annoyance eating at you over years.