When to tell someone "you suck!"

Why must I go through this torture? They make me read this junk and I have to critique it and say nice things but all I want to say it you suck! This is junk you should never write you will never be a writer this is generic, it is stupid, it makes no sense, how can you call this writing??? It has horrible spelling, grammatical errors, confusing sentence structure.

But then I think, what if someone said that to me? Would it crush my dreams of ever being a writer? What if I was really a horrible writer and I needed someone to awaken me to that?

I know I shouldn't be mean but it is so hard to not be harsh and blunt when I am suffering through every word of what could barely be called writing.

Ahhhhhhhhhhhhhhhhh!!!!!!!!!!!!!!!!!!!!!!!!!!!!