You can explain me

Dear Friend,
I know you since a while ago... Well, it may take forever to know everything of you, so, I can only say I "know" you... That's not the point of my letter anyway.
I'm confused of what is a friend. If you could please explain me what is a friend for you, I may solve some doubts I have. Because there are some things you do, I really don't understand. The concept of "what is a friend" differ from one person to another. I accept without hesitation the way people are, we can't be the same. That is what make the world interesting: different opinions, variety with preferences, etc.

People have secrets, I can't blame you for that. But, is that a reason for you of being someone else when you are with me? Why you hide many things with me, things that with others you express freely?
I don't want to judge you, I can't judge anyone, but sometimes you leave me with such an uncertainty...
Sometimes I feel you use me... Like you only want my services for your homeworks. I like to help, but there are limits. Sometimes you yell out loud my defects, making me look like a bad person. It appears like you want to affect me.

In the past this was different... We had fun singing songs, "dorkin' around", sharing our thoughts, trusting each other, doing many cool things. Now, it seems everything was fake.
What happened? You know you can tell me.

I'm writting you this letter so we can speak out what 's going on, so we can fix what it is left of our friendship. I write it because I still appreciate you. Please, don't ignore my intentions. We can still do something.

Sincerely,

your friend.