Some might reply: “But I will create a huge mess by letting the wronged parties know about my sin. Aaron, your Swatch story is child’s play compared to the mess I would make and the people I would hurt.”
The key is to understand that, as Andy Stanley said, “confession doesn’t hurt people, sin and concealment hurt people.”—What’s Your Secret? pages 68-69
As much as it might hurt, he's right. There was a line by Billy Crystal in City Slickers. His macho buddy was giving hypothetical situations where sex outside of marriage might be ok. He creates a real whopper: some alien comes to earth and wants to have sex with him. No one will ever know; the alien will step off the spaceship, then back on without detection. Billy Crystal's response was excellent, "I'll know." That sums it up.
You will know. It will haunt you and overshadow your life. Unconfessed sin always does... (No, I haven't sinned against my wife sexually, but I've done sinful and hurtful things against her and tried to keep them secret. It doesn't work...)