what is it with the words 'i don't care' dont people understand?

Yesterday wasn't the happiest day of my life. People not thinking before they speak or not taking into acount how much it would hurt another person. i'm not saying that i don't listen to how much my friends are hurting, it's just i overload sometimes and well i explode with frustraion. Some take it the wrong way but others they just don't get it. 'i have exploded with fury and yet you still babble!'. Take me seriously please, i hate not being heard!