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 tell guests your wedding is canceled, use this factual base: lead with the confirmed event, what it changes, who already knows, and any practical next step.
Reduce the work of responding
Offer simple options, a narrow question, or a clear update that can be understood without another conversation. Say what support or decision is needed now and make clear when no response is required. Make the immediate next step clear enough that the recipient can answer without reconstructing the entire history.
Respect the boundary already visible
Do not hide the central fact behind a long preface, speculate, or offer reassurance you cannot support. For death, abuse, medical emergencies, legal danger, or immediate safety risk, use qualified and urgent support first. A block, explicit refusal, legal restriction, or safety plan takes priority over the desire to explain more.