I have often regretted my speech, never my silence.

Things said in a heated moment stay with you in a way that things left unsaid do not. Silence occasionally costs you an opportunity, while speech that went wrong can cost you a relationship, a reputation or a night’s sleep. The two risks are not symmetrical, though they feel it at the time.

When the pressure to respond is highest, that is the moment to wait. Draft the reply and send it in the morning. If it still needs saying then, it will be better said, and quite often you will find it did not.