And I did cry a lot, on ep 14 when Heon Jae told her mom her condition, it was the saddest part for me (coz I can relate!).
But surprisingly after that scene there was no major crying. More of acceptance, understanding and lots of love.
I thought Heon Jae will die on the end, though it is still implied that she would, the story shows her living each day without regret. She was asked by Ji Wook if she would rather not be sick, she said if she isn't she wouldn't have the courage to change herself, to speak up, meet him and let her mom remarry, etc.