[His day has been so bad that he doesn't understand what Tadashi is telling him at first. At best, he hoped that he'd be able to talk to Tadashi.]

How - [???] That's not possible. You - the fire. We had a funeral for you and Callaghan said - he said he left you there to die.

[That's not really what he said, but it's what Hiro took away from their exchange. All he can remember about that moment is being so angry that Callaghan was alive and Tadashi wasn't.]