Oh, Merlin - it hadn't occurred to Harry that people might not have seen him get up and fight. He knew that some people had seen him, even if only fleetingly, in the midst of everything; now that he thought about it, though, it made sense that they probably were no more aware of where he was or what state he was in than he was of them. Except, that meant they all thought he was dead.
"No, I didn't," he said. "I let Voldemort kill me, because I had to - but it didn't work, Dumbledore knew it wouldn't. I'm alive. I - everyone thinks I'm dead, though, don't they?"
The words, once he'd started to speak, wouldn't stop tumbling out of his mouth. He instantly felt bad for not concentrating on Ginny's particular distress right at this moment, and reached out to hug her, arms going tight around her shoulders. "I'm alive, I'm really alive. I promise."