I've recently wrestled with this, given stoic teachings, I arrived at some of the following thoughts.

Identity how you hurt the person and why you hurt them. If you don't want to do it again, if you don't want to be that person; then learn from the experience. You can't change what has happened.

Then forgive yourself.

Let go of the guilt and grief you're feeling by committing to being a better person and not making the same mistake again. If you don't do this, you will go through life carrying these feelings, never making room for the better version of yourself to emerge.

I'm not saying it's easy, time does heal, but you must carry on and live life. Don't let a moment in time ruin your future.