Daryl gritted his teeth because he understood what Karen was implying. For years, he had been asking himself why his mother would waste her life on drugs and alcohol just like that night. And he had always assumed that his mother's depression because of his father had cost her her life when she was driving back home that night.
It turns out that it was not really what happened. It was not an accident, but a carefully hatched plot by the monster in front of him to deliberately kill his mother!
"So you are admitting that my mother's death was not an accident alone? That you are responsible? You drugged her and staged everything to look like an accident!" he growled, trying to control himself from smashing the glass that separated him from Karen, to grab the woman's neck and kill her at that very moment.