do you think it's easier for you to recommend this plan of action because, in the end, your ex-husband chose to behave responsibly and karma also intervened? sounds like you were in the right situation for your advice to work, but not everyone is so lucky.

many people post here because their partners cannot be trusted to behave responsibly. gambling that they suddenly will start doing the right thing, but only if you don't upset them by drawing any attention to the harmful things they've done, is exactly how many of these people convinced themselves not to leave their SOs earlier on when the bad behavior first started- it allows the responsibility for the SO's actions to be shifted to OP.

the person who consistently stands to benefit from withholding this information is not OP. the welfare of a child should never be a bargaining chip, explicitly or otherwise- whether or not OP calls an adulterer an adulterer when divorcing his sorry ass should have no bearing on how he parents his child unless he is a completely unfit parent.