This question really has many parts to it.
Is confessing to the spouse required in order to be forgiven by God? No.
Does a spouse that is cheated on deserve to know the truth? Yes.
Will the revelation of that truth lead to divorce? Statistically, yes. But just because it will doesn’t mean that revealing it is wrong. A person deserves to know whether or not they are married to a cheater, and then they can decide to stay with them or not.
Why did the person cheat? Just because they went to confession doesn’t mean that they won’t do it again. If it is a character flaw, then most likely they will do it again. The injured spouse needs to know who they are married to, because I think that cheaters tend to cheat, and more than once.
My advice? If you want to avoid divorce, don’t cheat, not even once. If you did cheat, don’t be surprised if the person you cheated on wants to divorce you.
Can a couple get through a situation like this? Yes, with God’s help, it’s possible. But the injured person still deserves the truth. At a very minumum, the injured person may have been exposed to an STD, and may choose to abstain from relations with the adulterer until proven clean of disease.