Clarify the agreement that existed
Identify the promise, policy, schedule, ownership, or shared understanding that applies before assigning blame. For a message about how to apologize for not helping with family care, use this factual base: describe what you did, the family context it affected, and any responsibility that still needs attention.
Resolve the next dependency
State what is complete, what remains disputed, and which action would move the situation forward. 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.
Document without threatening
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. Keep a factual record and describe only remedies you are entitled and prepared to use.