So yep, the OP is projecting her own selfishness. She's just a cousin, not close family, and no exemptions should be made for selfish people, ever. Really glad she's not going, for the sake of the bride and groom.
And, of course she is not REFUSING to go as nobody is trying to make her. She was just offered a lovely, polite invitation to have a lovely time, free food and dancing and fun with family. She's decided to decline. For her own sake, she should decline politely, but she sounds just about entitled enough to embarrass herself and make herself an outcast.
But really, how many more of these weird threads do there have to be? Every single time someone screams BUT MAH BABEEEZZZ and acts coercive, selfish and controlling over other people's weddings they are shot down in flames.
Every single time the vast, vast, vast majority tell these crackpots that no, they can't take their children to a child free wedding and no it's not even remotely selfish to have a child free wedding and that it's totally normal and has been going on forever not to have kids at your wedding, if that is your choice.
But they still keep coming, hoping that their selfish, over privileged coerciveness will be rewarded by agreement.
It's always going to be the same answer. So can we just let this nonsense go, forever?