While the following seems to indicate that a person can be assumed to repent from serious crimes such as sexual transgressions, the Chofetz Chaim doesn't address the need to get forgiveness from those the sinner hurt.
Chofetz Chaim(Lashon Harah 4:4): However if it seems to them that the sinner knew that what he did was wrong and he deliberated sinned e.g., prohibited sexual relations or eating unkosher food where the knowledge that the deed is prohibited is widespread – then it depends on the following. If he is an average person in other matters and he normally guards himself from sin and in this matter he was observed transgressing only this time and he did it secretly – then it is prohibited to reveal his sin to others even not in his presence. The one who does in fact reveal his sin has done a severe transgression because it is possible that the sinner has repented from his evil way and is upset for sinning and has been forgiven by G‑d. That is because the essence of repentance is the upset the sinner feels in his heart. Therefore when the sin is told to the public, he will be despised and degraded in their eyes – even though his sin has been forgiven. Therefore the one who reports it has done a terrible transgression. He should not reveal it even to the judges of the city, - even if he has a second witness to establish the veracity of the report. (That is because if he doesn’t have a second witness it would be forbidden to report it because it is prohibited for the judges to believe the report of a single witness. The single witness who reports it will be considered as simply saying lashon harah as we discuss later.) Thus he can’t report it because there is no benefit in doing so. However he must chastise in private the person who he saw sinning because the sin is a rebellion against G‑d. The sinner must be told that he must take extra care in the future not to sin again by avoiding the circumstances which encouraged him to sin. It is also important that the chastiser rebuke the sinner gently in order not to embarrass him…. All of this care not to publicly reveal his sin is even if the person is only average in his observance of other matters. So surely if he is a talmid chachom and G‑d fearing man who was temporarily overcome by his lust, it would definitely be a great sin to publicize his sin and it is prohibited to even suspect that he is continuing to sin because he certainly has repented. This is true even if his lust overcame him on one occasion because he is surely greatly upset at the sin. This is stated by our Sages (Berachos 19a), If you see a talmid chachom sin at night – do not suspect him of repeating that sin in the day because he definitely has repented.