This piece is very sad and hearfelt, but there are some corrections that need to be made:

"Only if they knew,
what i've been Thru.
all the sacrifices,
then they'll have a clue.
they will know why i cry
why i want to die."

First off, all of your "i"s should be capitalized, just proper grammer.

In the second line, "Thru" doesn't need to be capitalized.

"how am i going to make it threw."

"threw" should be "through".

"I just want all this to end,
cause i feel as if my heart has bend."

In the second line, the last part doesn't make sense. Shouldn't it be "my heart has been bent"? I would reword it because if you still want it to rhyme you need to change it.

Just fix those minor errors, and this poem will be much better. But besides that, I did like this piece, very heartfelt and you worded it well. Keep writing, always and forever...