what is the cure for chronic worrying?

Everyone else (here), I think

You've got to combat those worries with positive thoughts. Examine other, more positive outcomes to the situations you're worried about, and try to focus on them. It can also help to play out that worst case scenario in your head, and devise a plan for how to react if it were to happen - so you feel prepared, and in control. And realize that, even if it did happen, generally speaking - it wouldn't be the end of the world.