collect (one's) wits

To try to calm oneself and think clearly and rationally. Take a moment to collect your wits, then tell us how the accident happened. I know you're angry, so you need to collect your wits before you go in there and say something you'll regret to your boss. I needed to collect my wits so I could explain my side of the story, but I just couldn't stop crying.

If you collect your wits or gather your wits, you make an effort to control yourself and become calm again, after a frightening or shocking experience. I took a deep breath and tried to gather my wits. The news was so shocking that I was scarcely able to take it in. Sinking into a leather armchair, I attempted to collect my wits and decide what on earth I was going to tell Lucy.