Never! As a peace loving person, when I am faced with a condition where the other party is aggressively argumentative, and I am innocent, I would keep cool, allow the person to cool off, and wait for the right time preferably when he or she is calm to express myself. I will never allow anyone to intimidate or manipulate me into taking a blame for what I did not do.
When an argument is becoming too heated up, the best action is to walk away, never allow yourself to be manipulated, apologizing is saying "I'm guilty."