The first clue that she had that the Dark Lord was in truly dire health was the mere fact that she'd been back from her defection for almost two weeks and hadn't been summoned to the castle once. She wasn't sure all that her husband was keeping hidden from their master about the past year. Considering the summonses had been few and far between before she ran, she knew that it was theoretically possible that Antonin simply hadn't divulged the full truth to their master at all. Out of fear for her safety and what would happen if she was captured, he might have even been able to lie convincingly for an entire year. Her husband was a master Occlumens, far better than anyone she'd ever known. If anyone could do it, he could. When he was less agitated and no longer upset from what was clearly a trying evening, she would carefully press him for details of what he told the Dark Lord about her absence.