I love how in season 2, Peggy is just so tired of dealing with Jack that she doesn't even bother being sassy with him anymore. She's got him figured out: He's a good guy who gets insecure and makes bad decisions. There isn't much she can really do about that. That's how we get their scene in 2x08 where he's expecting Peggy to get argumentative and try to defend herself, and she just bypasses all of that and gets to the root of the problem.
"You're willing to believe any phlegm Vernon coughs up on paper because you're worried I would betray your trust. I wouldn't."
I think it's especially interesting given what came before (Peggy using Okinawa against Jack during their argument in 2x03) it's almost an apology on her part. My reading of that scene in Better Angels is that Peggy knows as soon as the words come out of her mouth that she's gone too far, but she's too stubborn to take them back. So she's using this as a chance to assure Jack that she is trustworthy, that she knows this about him but won't stoop to his level. She's also totally calling him out, acknowledging that he's only doing this to her because he's afraid.
Then she ends the conversation by giving him a (fairly backhanded) compliment. She totally refuses to engage with him. She doesn't even read the file!
Jack has no idea what to do with this! But it's such a good scene because Peggy's confident and self-assured reaction really gets him questioning Vernon. Peggy doesn't react at all like Jack would if someone confronted him about Okinawa. So he's forced to realize oh, this file is probably a forgery, maybe I am on the wrong side. It sets up his decision to go against Vernon and back Peggy in the next few episodes soooo well. The character development in this show is truly all I could ever ask for.
(Also, I really wish we got full outtakes of that scene, because what did Chad do that was "just godawful" lol)