Jewish approaches to uncertainty/need for comfort

I write this now from the waiting room while my wife is getting a colonoscopy. I have no reason to think it will go wrong. And yet.

Moments like this force me to stop everything else going on in my life and come face-to-face with the most horrible what-ifs: what if my wife becomes terribly sick and dies? Or my mother? Seems like my own mortality is easier to contemplate than either of those (no kids, in case you wondered the lack of a mention).

As I sit here in the waiting room, I wonder if our faith has given any of you a way to handle this kind of uncertainty and if so, what is it?