All hope is not lost when one falls into sin, the writer in Galatians 6:2 says to restore them. “Brethren, even if a man is caught in any trespass, you who are spiritual, restore such a one in a spirit of gentleness; each one looking to yourself, lest you too be tempted.”
To restore is to bring back or reinstate. When we sin against God, once we repent, He restores us into fellowship with Him, wiping the slate clean.
When it is in your power to do so, if one repents you should restore them, acting like it never happened, wiping clean the slate. The writer warns to look to yourself that you do not sin also by not forgiving them.