When our middle daughter was ten, and started voimitting and looking seriously ill. Visit to Accident Unit confirmed appendicitis, and surgery in the next hour. the worst bit was, as we followed her trolly to the theatre, the Nurse said "You can say goodbye to her now ..." and my rational mind kept telling me it was routine surgery, and my emotional mind kept saying "What if she doesn;t come back?"
Last year, driving to Glastonbury, I was in a seriously busy section of motorway, doing seventy in the middle lane. A car swung over from the outside lane without warning, and cut the gap in front of me from two car lengths to about three inches in two seconds. Without time to check my mirror, I swung over into the left lane to avoid hitting him, knowing that if there was anything there it was pile-up time - but there was space for me to fit in. i spent the next hour driving at 40 m.p.h. in the slow lane saying "Oh god ... oh god ..." to myself, and as an aetheist, that shows how deeply traumatised I felt.
Worst of all - complete nervous breakdown, admitted to psychiatric hopsital for three months, a year off work, and daily fear of never regaining sanity which had genuinely taken a holiday. OK now - medication for life, but never a day goes ny without the thought of what was, and could be again.