Mathew Byrne is insane. I never imagined he would become this deranged, harboring such twisted feelings toward me. He stalked my boyfriend of two years during a business trip, capturing photos of him intimately kissing a strange woman on the street and entering a hotel together. As he watched me break down in tears, he cruelly pointed at the kiss marks on the woman’s neck, his voice filled with seemingly genuine concern: "Now you finally see who he really is, don't you?" I slapped his hand away and glared at him, my eyes burning with rage. "Mathew, don't forget—I'm your sister." Mathew's eyes turned cold as he smiled. "Of course I haven't forgotten. But you, sister… why don’t you call me Mat anymore? You used to love calling me that." My palms trembled as I backed away, but I couldn't escape his advance. His warm breath brushed against my ear like a demon's whisper. "Crystal, call me Mat one more time."