Name the impact without exaggerating it
Describe who had to wait, worry, redo work, spend money, or make a choice with incomplete information. For a message about how to leave a band respectfully, use this factual base: state the role, agreement, effective date, unfinished work, property, access, and any transition obligation.
Make repair practical
Offer the repair you can actually complete, with ownership, timing, and any limit stated honestly. Give a clear ending, complete the required handoff, and name what support you can realistically provide. Make the immediate next step clear enough that the recipient can answer without reconstructing the entire history.
Let future behavior carry the proof
Do not disappear, promise indefinite availability, or use the ending to relitigate every grievance. Follow contracts, safeguarding, data access, employment, custody, and legal requirements before the role ends. A promise inside a message is weaker than a visible change in what you do after it.