Complex sentence: Returning to the house, Marie interrupts Julien preparing to hang himself in a desperate attempt to join her, and he runs to the kitchen and tries to slit his wrist, but she grabs the knife and he cuts his hand and her wrist.
Split into simpler sentences: Returning to the house, Marie interrupts Julien preparing to hang himself in a desperate attempt to join her. He runs to the kitchen and tries to slit his wrist, but she grabs the knife and he cuts his hand and her wrist.