When we do something wrong physically, our bodies react and they hurt. Like if we have a scratch, or a cut, or colds and flus, we know something's wrong and we feel uncomfortable.
When we do something wrong mentally or spiritually, our bodies probably won't react as much, but our souls can still feel it. Sometimes it's guilt, sometimes it's shame, regret, most of the times it's just a yukky feeling that's hard to put down to words.
Sometimes the yukky feelings can disappear in a day or two, other times it takes a long time or even stays and does damage to our total being. It can become a torture. Some people never got over them and live in that feeling for the rest of their lives.
We all make mistakes. We all sin. We all do something wrong sometimes, even intentionally we're trying to do something good.
God doesn't forsake us for our sins. He says, if you repent, I'll forgive you.
As Christians we're all well taught about forgiving one another. That's the key to let go of the hurt and damage that other people have done to us.
But what about ourselves? This is something I used to neglect. The Lord showed me once that the biggest person that I need to forgive is myself. And that revelation has brought a huge relief and freedom in my life.
So, when you do something wrong, and feel yukky, find out where the mistake come from, repent of it, learn from it, do whatever you can to mend it, then genuinely forgive yourselves. It doesn't matter if other people have forgiven or forgotten about your mistakes. It's none of their business. When you genuinely forgive yourself, you'll find that amazingly those yukky feelings will go very quickly and you'll be happy again.