As You Exit a Shopping Mall You Accidentally Run into Another

As you exit a shopping mall you accidentally run into another person and knock her down. As she leaps to her feet you begin to exchange words that escalate, and you find yourself in physical struggle with the other person. After receiving several blows from her you retaliate by striking her on the head with your umbrella, knocking her unconscious and producing a large gash on her head. Discuss the principles of assault and battery as well as self-defence and what actions constitute each by defining them. Write a short decision on this case based on your knowledge and definition of the principles.