Yes, I agree with that. Remember that when a wrongdoing is committed it is not only against the person concerned but also against God. It always has the horizontal and the vertical element, man and God. That’s why when the Prodigal Son decided to go back to his father, he said, ‘I have sinned against you and against God’. Similarly when we wish something bad against another human being it effect is felt by God as if we are doing it to God. Therefore apology too needs to be made to both. Thus confession is necessary. Similarly in the case of theft. We may return the item stolen but we also have to be right with God too. That can be achieved only with confession.
Only you may ask, whether it is a venial or a mortal sin? If you are undecided, then it is better to confess it. For we can never be up to the glory of God.
God bless.