I mean she also likely was wrong about Bayonetta being a half a billion dollar IP.Assuming this is true why would she lie about the amount?
She could have made the same point about being underpaid without lying about it.
I would imagine there must have been emails at the very least containing the discussion on what she would be paid. She could show them her side of it as well.
That said I have no idea WTF happened here. I wouldn't suggest jumping to a conclusion either way. I am sure the truth will come out and it probably won't take years for it do so.
Only way to really disprove her would be Platinum or Nintendo showing the offer or contracts which they will never do.
She thought she was irreplacable and Bayonetta was a MUCH bigger IP thna it actually is. Thats a combination of two bad things when you wanna negotiate seriosly.