Élise shows up on stage and Harpagon accuses her of betraying him. But he also tells her that he plans on imprisoning her in his house and sending Valère to be hanged. This guy is really keen on the whole hanging thing.
Élise tells her father that she would be dead if it weren't for Valère, since he saved her from drowning years before.
Harpagon tells Élise that he'd rather she have drowned than to have her betray him like this. Yeah, that's pretty harsh.