Unfortunately life doesn't hand out do-overs, which means each of us is left with a portion of internal regret over past mistakes made. However difficult regret is to bear, if you are in fact truly sorry, then you will move forward with the knowledge from the experience and the wisdom of how to act in the future.
For the next time, think about possible outcomes of your decisions and how they will impact those around you. You aren't expected to be perfect, nor should you expect others to be perfect either. If together everyone works at being a little more thoughtful, a little more honest, and a little more loving in each and every moment, we will have a renewed trust in those around us, so there will be no need for sorry.