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 family you are joining the military, use this factual base: explain what is changing, when it takes effect, what remains private, and any practical impact on them.
Offer a proportionate next step
Match the size of the request to the relationship and to what the recipient can reasonably decide now. Share the news directly and invite only the questions or support you are ready to receive. Make the immediate next step clear enough that the recipient can answer without reconstructing the entire history.
Protect privacy on both sides
Do not make one recipient responsible for announcing it to everyone or defending your decision. Plan privacy, housing, medical, employment, and personal safety before disclosing a change that may trigger retaliation. Use the most private legitimate channel available and do not share the exchange to recruit support or pressure.