Recognize what makes this moment difficult
Acknowledge the event directly without turning it into a lesson, comparison, prediction, or silver lining. For a message about how to apologize for criticizing someone's parenting, use this factual base: describe what you did, the family context it affected, and any responsibility that still needs attention.
Offer support that can be accepted
Offer one specific form of practical or emotional support and make clear that no immediate reply is needed. Make a direct repair to the affected person and change the practical pattern that caused the problem. Make the immediate next step clear enough that the recipient can answer without reconstructing the entire history.
Follow their pace rather than yours
Do not invoke family loyalty, childhood history, or a holiday deadline to force reconciliation. Keep children and vulnerable relatives out of adult conflict and follow any safeguarding or court requirements. The recipient decides whether they want conversation, ordinary company, practical help, professional support, or quiet.