Is the house haunted, or is Julia suffering from a psychotic break induced by trauma?

. However, being back in that environment forces her to confront "ghosts" and dark memories that begin to manifest in the present in unsettlingly real ways

Julia’s secret was twofold: the fire hadn’t been an accident. Her father, a respected industrialist, had killed a rival to protect their empire, and the rival’s vengeful sister had set the house ablaze in a final act of desperation. Julia’s mother, too shaken to speak, had smuggled Julia away the night before the fire—and died trying. Yet Julia, raised on lies by her father, believed the fire had been her fault.