[As far as Crowley is concerned, the nail is in the coffin the second that Aziraphale doesn't turn to look at him after he offered an easy out. Either he could have denied it, and Crowley would've dropped the subject, or he could have lied, and Crowley would have left it, too. Which may have made the whole exercise pointless, but he'd have known, if Aziraphale had lied to him, that the horror of doing this outweighed everything else, and he wouldn't have been cruel enough to push, had that been the case.]

At least neither of us got stuck with the Slaughter.

[He still would have offered, but he knows that taking secrets is nothing compared to how reticent Aziraphale would have been to actually cause physical harm.

Hypotheticals don't really help anyone, though, so he keeps any further thoughts to himself as he waits for Aziraphale's decision, already fairly confident he knows what it is.

The worst part is that winning the argument brings little relief, now that he has to give what was offered.]

Thank you. [It's a horrible thing to thank him for, but he wants to make it clear that he knows how much of a struggle this is for Aziraphale. He's thanking him for not fighting it more, and for being willing to look after himself, even if it means some discomfort for Crowley.] What's the best way to do this? Do I tell you something, or will it only work if you drag it out of me?

[The Web tends to give him a sense of what would be satisfying, a little nudge at the back of his mind. It's probably similar for Aziraphale.]