Yes, I have a stone heart

When someone first told me that I have a stone heart, I felt like throwing a brick right at his/her face. When you do so much for a person, you at least expect a little appreciation in return. It is human nature. But then when you get blamed for that one mistake you made, or that one sin you committed ,knowingly or unknowingly a part of you dies. Permanently.
So when that one person whom I trusted more than anybody else, blamed me for that one mistake of mine, I felt the world around me coming to a grinding halt. I had a world of chances for that person but I wasn't even given one chance to improve upon. The truth was yet blurry but the lies were getting clearer. It was a moment of deep realization, retrospect. And at that very moment, I decided to change myself. Change myself for good. Stop feeling any deep emotion so that I don't fall apart when something of this sort happens again. I was so close to becoming a sadist. And this change not only had adverse affects on me, but also on the people around me.
So go ahead, tell me that i am mean, manipulative or maybe that I have a stone heart. But it is because of the stones you threw at me that I have developed a stone heart.