heavy truth

Does the expression ‘heavy truth’ exist? I’ve found it in several articles , but my teacher says that only ‘hard truth’ is the correct usage.

“heavy truth” is not really a set expression, but it’s not incorrect to use that combination of words. It suggests that the truth is burdensome and unwelcome.

so i could use both right(hard true and heavy true)?

Do you mean “hard truth” and “heavy truth”? If so, yes (provided the context is suitable of course). “hard truth” is more of a recognised expression and is more common. The connotations are not quite identical.