Heartbreakingly is the adverb. It tells you how something happens, or how someone or something seems, in a way that makes you extremely sad or disappointed. It usually leans on an adjective or a verb: heartbreakingly sad, heartbreakingly honest, they came heartbreakingly close, she smiled heartbreakingly. Heartbreakingly close is a set pattern in sport and in news: you almost won, and the almost is the wound. Heartbreakingly beautiful is a stretch people like — the thing is so beautiful it almost hurts — and that use is more about intensity than about grief. The word is fairly literary. You will meet it in reviews, headlines, and careful speech more than in the playground. Though actually, speakers also use it lightly, the same way they stretch heartbreaking, so the temperature is not always as high as the pieces suggest. You would not normally say I am heartbreakingly; the adverb wants something to modify.

令人心碎地（修飾後面的形容詞或動詞，如 heartbreakingly close）