I cannot trust anymore because of you

You promised me I would be your best friend forever,
You promised me we would always be together,
But you broke your promises,
And you left me broken in pieces.

Why did you have to do that?
I trusted you and you broke my heart apart...
You shared your secrets with me,
And I felt loved, I felt you were the key.

But now I know, I know how you are,
I know you're not at all the shining star,
And I will not let you break anyone else,
As I will tell everyone your real personality.

I just wanted you to know,
That I might have been very low,
But now I'm OK, and I will not let anyone use me like you did,
As because of you, I cannot trust anyone anymore...

As English isn't my mother tongue, I don't know if every thing -Really- makes sense, I hope you understand it, I just had to express my feelings.