Make room for the other version
Ask what the other person understood before assuming that you are arguing about the same facts. For a message about how to correct a false family story, use this factual base: state the claim, where it appeared, what can be verified, and who actually needs the correction.
Correct the record precisely
Correct only what you can support, acknowledge any real impact, and propose a practical way to prevent repetition. Ask for a correction, removal, or direct conversation and keep an accurate written record. Make the immediate next step clear enough that the recipient can answer without reconstructing the entire history.
Agree on a testable next step
Do not publish private evidence, speculate about motive, or recruit an audience to punish someone. Use school, workplace, platform, legal, or police channels for threats, defamation risk, intimate material, or impersonation. Do not recruit an audience, publish private evidence, or turn a misunderstanding into a campaign about character.