[Valpal1]

She knew that he carried that gun with him and into that theatre and that he was working himself up to use it.

That's stretching it a bit, since apparently he has carried a gun most of his adult life and never used it before. So exactly how would she know he was working himself up to do something that he'd never done before?

[Uncle Chip]

So exactly how would she know he was working himself up to do something that he'd never done before?

Well they had been married for 50 years so I'm assuming that she has seen what he can do when he gets angry and in this case that thing he could do it with was right next to her with his hand wrapped around it.