Okay, not really your mistakes. But those your characters make. By the end of the novel, do they need to own up to their mistakes?
As authors, we want to create characters that grip the hearts of our readers. This means that we put them through horrible things. We make them choose things that some might see as "wrong" or that could be illegal. We do this to show them as 3-dimensional, real people.
All these bad things your characters go through is good. The bad choices they make are even better. I mean, the more layers your characters have, the more levels on which your readers can find a connection. (I mean, come on. How many of us have made bad decisions? Go on, raise your hands. Yeah, me too.) Those are the characters we identify with, the ones we love--the ones who are imperfect yet lovable.
Because that's how real people are.
So back to the question at hand. At the end of the story, does the character have to own up to the things they've done wrong?
My advice: Make it authentic. If a punishment is necessary for character growth and plot development, then yes. Absolutely make your character go through that ring of fire and brimstone. Give them emotional consequences. Real-world consequences. Allow them to grow. And allow us to experience all of that with them.
Now, that doesn't mean that every little infraction they've committed has to be brought to light. In real life, people get away with things all the time. I do believe, however, that if you bring your characters to the fire--and then pull them through it--your readers will identify more strongly with them. Think about it. Who wants to read about someone who gets away with everything? Never has to pay for a mistake? Go on. Raise your hands now. Mine's not up, because I'd rather experience the growth of a character that comes from learning the hard way.
Creating memorable characters is essential in good fiction writing. If you make them pay for the (major) things they've done wrong, they'll be richer, deeper, unforgettable. So go on! Make them suffer, just a little bit more.