What is it?

I try to be understanding
i try to keep on trying
but sometimes things just get to hard
and i start to cry
u may not see me
but i do
i feel as tho sometimes u use me
for things u cannot do
for people who u cannot see
and i can
do u understand
i try to take it
i try to forget it
but it gets me
and i feel so used
so not worthy of ur friendship
so what is it
are u my friend
till the end
or ami someone just here
to get u what u want
what is it
i need to to know