what is your most heart breaking things in your memory?

For me the most heart breaking thing is my big sister passed away, she is a very happy and talent women. I remembered very clearly,that day was my most disaster day in my life. After i came to my home from my college, my dad told me my sister passed away. I cried loud. All of the three years, I do not know how i spent these days. I am very depressed, now more than 10 years passed. I just recover from it.
What is your most miserable thing in your memory?