cry your heart out

cry (one's) heart out

To cry for an extended period of time. Poor Jane really cried her heart out during the funeral service. I can't watch those sappy movies because I just cry my heart out every time.
See also: cry, heart, out
Farlex Dictionary of Idioms.

cry your heart out

or

sob your heart out

INFORMAL
COMMON If you cry your heart out or sob your heart out, you cry a lot. Note: The heart is traditionally regarded as the centre of the emotions. I threw myself on to the bed and cried my heart out. I had never known her cry, and here she was sobbing her heart out. Compare with your heart out.
See also: cry, heart, out
Collins COBUILD Idioms Dictionary, 3rd ed.
See also:
  • cry (one's) heart out
  • cry heart out
  • cry one's eyes out
  • cry your eyes out
  • cry eyes out
  • cry
  • cry (one's) eyes out
  • cry like a baby
  • cry from the heart
  • a cry from the heart