Wow! Thats really good! My favourite lines where ""yes" i lie
because i can't tell them how i really feel inside,"
And I also liked "cause they only like me, because they think i'm fun
a girl who laughs all the time,
is smiling and dumb
they don't know what is inside, of this black heart of mine
and if i told them,
they would draw a line"
I can really relate to it! Well done!

I like the topic and you described emotions excellently, I know how you fell with fake friends around your self. You have few mistakes in this one, you used words:-I-understand-feel-because-inside-too- two or more times and that destroys flow. Anyway great poem with really good and original topic!