My Best Friend?

My Best Friend is a guy, we have known each other since we were like a year old. I am a girl. We talk all the time, were in the same cl at school. He respects girls and does NOT talk trash about them. He came over for my Birthday party and every year my cousin comes. Everyone hates my cousin because she is fat, ugly mean to the extreme, and annoys everyone. This year at my birthday party she punched me really hard. So my best friend that is a boy punched her in the face. So now my cousin can't come anymore =)! My bst friend usually dosen't punch people but he sometimes says to me "I get myself into bad situations". Do you think he did the right thing?