Why can't you go? She thinks she's going to be jumped by racists, does she think by going to a wedding that it means you're a racist too? What's going on there?

This does sound very controlling. Does your partner enjoy socialising at any other occasion? Would she be happy for you to go to any other kind of event? Honestly this sounds like social anxiety that's been left unchecked, but that's only because I've had friends behave similarly.

At this point it feels like you've known this friend long enough that they're practically family. You should go to the wedding.

It seems like there's two kinds of people who call themselves child free, those that don't want to bring a child into a world they think is getting worse, and those who just hate being reminded that kids exist.

It's ok to coexist with children despite not spawning any of your own. For someone that hates kids, this is quite an immature and selfish attitude you're showing...