Here is an interesting framework for being supportive. It applies to trauma in general but I think it could apply to the scenario you write about above:

1. Spend time with the stressed person, without judging or demanding. Their recovery will occur in its own time.
2. Offer support and a listening ear. Talking is one of the best things they can do to work things out – but they may need to go over things many more times than you expect. Try to be interested in what they want to say – avoid giving advice or trying to solve the problems. The talking itself is important and helps to make it fade. Remember though, this is likely to happen at their pace, not yours.
3. Help with practical tasks and chores as this enables more of their energy and time to be given to the recovery process.
4. Give them time, space and patience – don’t take it personally if at times they are irritable, bad tempered or want to be alone. These are a natural part of the stress response and will pass as they recover.
5. Don’t try to talk them out of their reactions, minimize the event or say things like ‘you’re lucky it wasn’t worse,’ or ‘pull yourself together,’ or try to get them to look on the bright side. Stressed people need to concentrate on themselves at first – they’ll feel supported if you let them know you are concerned, want to help and are trying to understand. They’ll see your viewpoint as they recover.

For more thoruough information, the link is below

https://www.health.govt.nz/your-health/healthy-living/emergency-management/managing-stress-emergency/when-someone-you-know-has-been-through-traumatic-experience