伤心 (shāng xīn) is the everyday word for 'sad, heartbroken' — it describes the emotional pain you feel from a disappointment or loss. It's more colloquial and personal than 悲伤 (bēi shāng, HSK6, a more formal/literary 'sorrowful') and 悲痛 (bēi tòng, HSK7, a deeper, more intense grief often used for tragedies).