Venerable Fulton Sheen
“The fact that we conceal sins makes them peculiarly our own. Then they are not just our fault; they are our very penalty. Any concealed fault lays a heavy burden on the soul over and above the remorse for the sin itself. The shame of having hid it in the heart always makes the hider feel as if he were acting a lie; he despises himself in the midst of every word of praise that he receives.”
Source: Ven. Fulton Sheen, These are the Sacraments