Write from facts rather than momentum
Pause long enough to remove accusations, assumptions, and details that belong to someone else. For a message about how to tell your manager you missed important work, use this factual base: use recent examples, observable impact, and the work requirement rather than labels about personality.
Offer a proportionate next step
Match the size of the request to the relationship and to what the recipient can reasonably decide now. Ask for a specific change, decision, or working agreement and choose a time to review it. Make the immediate next step clear enough that the recipient can answer without reconstructing the entire history.
Protect privacy on both sides
Do not diagnose, gossip, embarrass a colleague, or turn one incident into a judgment about their character. Move harassment, discrimination, threats, health risk, and retaliation into the appropriate protected process. Use the most private legitimate channel available and do not share the exchange to recruit support or pressure.