Broken Stone

A stone is cold and hard,
so how do you go about breaking one?
Simple... you give it a small chip,
and then watch it as it falls more
and more apart over time.

My heart was a stone, so cold and hard;
believed to be an invincible, unhurtable part.
Protected as it was, it managed to get chipped,
and now all it can do is fall apart and never mend.