You have some good ideas in your writing but it needs more impact especially at the start. Have you considered using the features of the setting first? Remember the heat is oppressive, even at night. There will be sounds of the traffic at the front of the apartment building, maybe even the noise of diners in the restaurant across the road, the sounds and smells of apartment dwellers preparing dinner (everyone has their windows open). Set the scene first, then move into Miss Lonelyheart's disenchantment - the fantasy date, the frightening almost-rape scene, the bickering neighbours (the Thorwalds) who might give you the opportunity for Miss Lonelyheart's reflections on her own marriage. You could even place her declaration of her intentions near the end - good shock value for your reader. Keep thinking of the sensory aspects of each stage of your piece - the smell of her attacker's after shave, the texture of his suit, her shock and disappointment that her risk-taking has failed. This might actually help you to better integrate your section about her distraction by the pianist's tune.