The killer looked at her, eyes shining.  Those eyes were almost as bad as what he had done.  His eyes were like deep black vortexes, drawing in anyone who dared glance at him.  She hadn’t been able to suppress a gasp as he pulled off the rubber mask he had been wearing to reveal the sweat-slick face of her ex.  The realization of it had sent a knife of pain through her worse than the knife wounds.
Her eyes unwillingly took in every detail of the scene.  His black hair, hanging down in front of his face.  His eyes, shining like a kid who was told he could get any piece of candy he wanted.  She glanced at his hand, holding the long medieval dagger her husband had been proud of.  He had showed it off so often, showing how the red metal looked as if the blade had been soaked in blood.
Now it was. 
It was her fault, telling her husband to go on his business trip.  She had lied, saying she and a friend were going camping secretly.  She wish she had told him about meeting her ex.  If she had, maybe she wouldn’t be lying here, seeing her husband’s prized possession covered to the hilt in her blood.  It made a steady dripping sound as the blood ran down the knife, only to spatter on the kitchen tiles. 
Finally, her eyes got to his mouth, grinning and open, spilling out a nervous chuckle, that repeated itself until it grew into a full sadistic laugh, seeming of glee, but full of pain and longing.  It made her realize… She was the cause of this man’s insanity.