agonizing vs heartbreaking

agonizing

adj
  • Causing physical or mental agony. 

noun
  • The act of one who agonizes. 

heartbreaking

adj
  • That causes great grief, anguish or distress. 

noun
  • The breaking of a heart; great grief, anguish or distress. 

How often have the words agonizing and heartbreaking occurred in a corpus of books? (source: Google Ngram Viewer )