Antonyms of the phrase "am overjoyed" include dejected, sad, unhappy, hopeless, sorrowful, miserable, and disheartened. These are emotions that one feels when something negative happens or when their expectations are not met. Being dejected and sad could result from losing something that was valuable to them, while being unhappy is a general feeling of dissatisfaction. Similarly, feeling hopeless could result from lacking positivity, while misery is associated with profound suffering. Lastly, when one is disheartened, they feel discouraged and downhearted. It's essential to acknowledge these emotions since they help us appreciate the joyous moments in our lives.