He was not going to panic. He was not going to take what she was saying personally. Even if he had been worried for the past couple of days that having a visible reaction regarding the loss of Lavender's database, he really doubted that he needed to give Marietta the feeling that she'd been right about anything at all. Plus, he didn't trust her, he didn't care whoever else happened to. That was their own misjudgment to deal with later on.
And he might have been a bit amused about her attempt to put doubt in him when it came to Michael just for the fact that it wasn't even possible. There may have been a lot of things he was blocking out from the conversation they had had the day before, especially the parts that had lead to awkward moments, but that didn't mean he had forgotten what had actually been said. Never mind that there were way too many years involved. What was more, he wasn't about to doubt the DA. At least, not in regards to abandoning everyone who was actually on Pandora's unwritten hit list. He didn't exactly know yet how positive he could be about fixing this entire situation.
Despite that, he couldn't really pretend that the main part of him wasn't focused on and very, very worried about the idea of being killed. If she had assumed that he was in the database, then she was just exploiting that. And it might have been working a bit. Which might have been why instead of replying verbally, he bit the inside of his cheek hard enough to hurt, his frown having turned into a glare. She didn't know anything, he told himself. Or tried to tell himself in any case.