Why life is so cruel to some people?

Shall I be selfish?Shall I ignore peoples' bad points and keep doing what I want?I don't know,maybe it is true that my mind is so unchangeable,but this is not what I want to be in life.What does life mean?How can we live?I can't stop thinking about all these things,I can't be as ignorant as other people are,I can't,I know,I am stubborn,God,why shall I be like that?Every one has it's own characteristics,but why are they so unchanged on me?
I am sad,I feel so sad when I hear defeats and sorrowful happenings in people's lives.I have always wanted the best for them,I have always prayed for them,but now...I can't express my sadness,no,now I know that I can't ignore people's troubles,I can never do it.I can't act agaist what is on my nature.Although I know that it is possible,but I would hate my self,if I do such thing.I'll have my own life,but it would not be far and regardless to others.I know I can't donate every one peace,but I'll do my best.God!I can't express my sorrow,I am really shocked and upset.How could it happen,while I had so much prayed?Why life must be so cruel,dark,and hard for some people?How can it plunder such joy and youthfulness?WHY?I wish I could do some thing,I wish I could help in some way,How can I?I can't live apart these people.Now I am sure about it.