I agree with you @krnel, truth is a synonym of reality because a person could not live in reality if he is not true to himself. A person who live in lies could not to be happy, they does but to some extent of outward happiness but the real that comes from within could not be achieve.

A lie slowly kills an individual, not a physical killing but rather a killing within its personality and the only thing that heal is the truth.

There's a saying that "the truth will set you free". This is true, a person who admits himself by saying the truth, takes out the chain that hid himself from the sun, the sun that gives life, and that is real happiness.