Good Friend Bad Friend

How do u define friendship? Who is a good friend? Is it someone who tells you everything and doesnt hide anything from you? Or is it someone who hides facts and shields you from the harsh truth to protect you?
From the definition of the word Friend - it says that it is someone who is true to you and all that? But I say, isnt it harder to hide the truth from your good friend just for the fact that your friend should not get hurt?
I am a person who takes a LOT of decisions in my head with respect to the people with whom I interact. I think and take a lot of decisions just in my head without discussing this with anyone. Is this because I think I am so great that I know what is right and wrong? Or is it because I CANNOT discuss this with anyone other than myself? Is it because there is noone around who would be able to listen to my thoughts without judging me or my friends and tell me what is right and what is wrong?
I take decisions in my head on what to tell and what not to tell based on how it would help or hurt the recipient. I told the truth to one friend so he would be able to use it to his advantage and learn from it. I hid the truth from one friend so that she would not get hurt.
Was I wrong in doing this? Now, does this mean I have discriminated between my friends? Does this mean I consider one of them closer to me than the other? Does this mean I am a bad person and more importantly a bad friend???
Why am I going out of my mind thinking about this? I thought I did things for the good of my friends. Taking the decision on its own ate my brain. Now I am worrying about the decisions I took, because it was not understood the same way I had meant it.
Am I just worrying too much or am I really a bad person and a bad friend? Unless someone gives me the answer to these questions, I think I am going to continue to be this Good Friend Bad Friend to everyone around me.
I am just afraid, this confusion and MY decisions might hurt my friends and my friendship....... I DO NOT EVER want to hurt my friends.