As a parent, I read a lot of kids' books. There's something really lovely about them, in general: when they're looking to teach a lesson or inform a kid, man, they are direct. No 100+ pages of examples or stories; just one straight narrative and a purpose. I love that.
One of my son's frequently-read books is Tumford the Terrible by Nancy Tillman. It's the story of a cat who makes mistakes and messes, and never says he's sorry... until one day he confronts his actual feelings and finds that telling the truth and apologizing makes him feel good. Deep, right?
It seems that the simple act of apologizing becomes a lot less simple as we become older. If we hurt someone, intentionally or not, we put up barriers. We may eschew responsibility and pin it on someone or something else. The email never left my outbox... this person doesn't speak for the company... it wasn't intended that way. But in my own experience, doing this makes me feel uncomfortable. It is a little nugget of a burden that sits on my back and becomes another thing I need to carry, need to nurture, even though it's deserving of neither.
If you already know the truth, then be brave and face it. It may hurt a little bit. But like Tumford, once that apology is out there... your self, your true and wonderful self, can heal.