Gemini said
My Sweet Killer (1999)
Plot: Charlie is an introverted, socially awkward man who has recently been released from a mental institution. He finds a job as a night janitor and moves into a dilapidated apartment, hoping to rebuild his life in solitude. However, his isolation is broken when he discovers the diary of the apartment's previous tenant—a woman who committed suicide. As Charlie becomes obsessed with her writings, he begins to lose his grip on reality. The line between his own identity and the deceased woman’s thoughts blurs, leading him down a dark, hallucinatory path of madness and murder as he tries to "reunite" with his sweet,