Suffering has been stronger than all other teaching, and has taught me to understand what your heart used to be. I have been bent and broken, but - I hope - into a better shape.

This quote means that throughout the speaker’s life, they have gone through a lot of pain and suffering. The hardships they have faced have helped them understand things on a deeper, more compassionate level. Although they feel as if they have been broken and bent in a difficult way, they still have hope that this experience has changed them for the better.