Wiktionary
heart-breaking
a. (context idiomatic English) That causes extreme sorrow or grief.
Usage examples of "heart-breaking".
They dismounted in order to revere it more at their ease, but the bust proved, by an irony bitterer than the sick, heart-breaking, brilliant Jew could have imagined in his cruelest moment, to be that of the German Milton, the respectable poet Klopstock, whom Heine abhorred and mocked so pitilessly.
At the same time, over his childish countenance which was, at once so impudent and so serious, so giddy and so profound, so gay and so heart-breaking, passed all those grimaces of an old man which signify: Ah bah!
There were of course the usual heart-breaking melancholias: people who had committed the unpardonable sin, had done the everlasting wrong.