Q 191 … When you have, told all your sins, you will say: “For these and all the sins of my whole life, especially any I have forgotten, I am heartily sorry, and ask pardon and penance!’ Listen to the priest’s advice, and answer simply any question he may ask you. If you should forget a mortal sin in confession and remember it the same day or evening, or while you are still in the church, it will not be necessary to wait and go to confession again. It is forgiven already, because it was included in your forgotten sins; but you must tell it the next time you go to confession, saying before your regular confession: In my last confession I forgot this sin. Of course if you tried to forget your sins your confession would be invalid. It is only when you examine your conscience with all reasonable care, and then after all forget some sins, that such forgotten sins are forgiven.