Why does she even need to "let you" invite more people? Why did she do the list by herself? What's up with her thinking that a 70/30 split is reasonable?

This isn't normal. You usually sit down as a couple, invite roughly the same amount of loved ones from either side of the family and friend circles, and you normally exclude exes from the guest list.

OP, I'm not trying to be rude and if I could think of a less harsh word than "doormat" that'd still apply, I would use it. But I don't know how else to put it. You sound like she's walking all over you, and her acting like she's the one who has cause to feel upset is a straight-up bizzaro world gaslight-ey tactic.

I think you need to be strict, assertive and tell her in no uncertain terms that she needs to get her shit together if she wants the wedding and subsequent marriage to work. You're supposed to be a team. You're supposed to celebrate your love, without the distraction of exes present.