The truth and nothing but the truth

is it best to know everything or to leave things unknown? cause some things you might not want to know. or admit to yourself. that's the problem that i always have. i hide the truth from myself. i think that it's easier to not admit some things to yourself. it makes life simplier in some ways? but at the same time it's not good at all. if you don't allow the truth to come out and be known then before you know it, it could be too late.