Make the first sentence usable
Lead with the reason for writing so the recipient does not have to decode a long emotional introduction. For a message about how to disagree with your manager respectfully, use this factual base: use recent examples, observable impact, and the work requirement rather than labels about personality.
Reduce the work of responding
Offer simple options, a narrow question, or a clear update that can be understood without another conversation. 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.
Respect the boundary already visible
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. A block, explicit refusal, legal restriction, or safety plan takes priority over the desire to explain more.