heartache vs purgatory

heartache

noun
  • Very sincere and difficult emotional problems or stress. 

purgatory

noun
  • Any situation where suffering is endured, particularly as part of a process of redemption. 

adj
  • Tending to cleanse; expiatory. 

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