Start with the part that is verifiable
Separate the event you can describe from the motive or reaction you are guessing. For a message about how to support someone living with severe anxiety, use this factual base: reflect what the person has told you, any immediate concern, and the practical context without diagnosing them.
Make one answerable request
Give the recipient one concrete question or next step instead of several emotional jobs at once. Offer one manageable form of support and ask directly about safety when you have a serious reason to worry. Make the immediate next step clear enough that the recipient can answer without reconstructing the entire history.
Leave the recipient in control
Do not shame, threaten, promise secrecy about imminent danger, or make yourself the only source of help. If someone may harm themselves or another person, contact local emergency or crisis services and a trusted nearby person now. A clear message remains useful even when the answer is no or no answer arrives.