Today I am Sad why?

I have always been very dedicated with myself and always tried to do the best for myself and for others. i have always tried to comfort others no matter if i felt discomfort . I have always been loyal to my friends. I always tried to be good with all the people around my society.
But what happened to me? Everyone around me took advantage of me. Everyone played with my emotions and and with my feelings. People whom i used to care about now laugh at me. And friends for whom i was there every time they needed me now think that i am not able to be called as friend.
I want to ask all the people that why the society is so brutal? Why always good people have to regret for their good behavior? If you can answer my questions then please do answer in comments.
In the end i want to tell you that if you think that people like us are weak then it your worst mistake of life. We can do anything if we want it is just matter of kindness and purity of heart.