A $23-$year$-$old woman is brought to the office by her parents because she has been withdrawn, confused, and unaware of her surroundings for the past two weeks. The parents say these changes began after the patient attended a party and witnessed an altercation during which one guest fatally stabbed another guest. The patient says she has had flashbacks of the murder that are sometimes vivid. Which of the following is the most appropriate initial management of this patient's condition?