I’m glad you are feeling calmer today – I hope that lasts. I think we often ‘regress’ at the moment of ‘challenge’ or ‘shock’ and it is easy to be temporarily thrown off course, but the ability to re-think , as you have shown, is of great help in these situations and ‘bad moments’.
Again, I really identify with those feelings about ‘control’ and ‘letting go’ with our grown-up children!
Your job seems to need a lot of your strength right now, so probably you just have to concentrate on feeling able to get on with that and looking after yourself.
I hope the chemotherapy is not too difficult for you.