"He who conceals his sins does not prosper, but whoever confesses and renounces them finds mercy" (Prov 28:13).
It's not really a comprehensive treatise (or a comprehensible treatise, at that!), but here's what I've been thinking...
Concealing our sins is not only bad for us physically and emotionally (see Psalm 32 for a description; you can also probably Google studies about the physical benefits of forgiveness - here's one, for example), but it also prevents us from availing ourselves of the mercy and grace that God offers to those who confess their sins ... both in the here and now, and for eternal life.
Concealing our sins also sets us up for bigger problems down the road -- in terms of how difficult it is to finally confess, how much of a stronghold that sin will have on our lives, and how inclined those affected will be to offer us grace.
I read an account recently where a man's wife essentially had him up on a pedastal -- and so he was afraid to admit his struggles to her. By the time she found out, she was devastated and he was terrified to admit any more than necessary to pacify her. She was also incredibly angry and essentially turned into his "holy spirit" -- anytime he went anywhere or did anything, she would question (and accuse) him to the minutest detail. He grew terrified of her (and of himself, since it's difficult to control the mind); he confessed things over and over without finding any freedom or grace.
We live in a fallen world ... struggle with sin is to be expected (well, actually, sin is to be expected; the struggle against sin is evidence of God's grace in our lives). In God's economy, there is freedom to confess, and a liberation, a healing, through the confession.
I'd like to be the type of person in relationships where quick confession does lead to mercy, so that we can live wholesome/prosperous (shalom) lives.