Remember, children, either overwhelm her in momentum, the worst case is not being beaten, but being called a coward by others.
Also, don't call first. If you really call, remember to call on campus, or where there are electronic eyes (monitored). It's self-defense to fight again in the future. Remember, when you are really cruel, you are welcome. Hit the chin or stomach (don't take weapons, like bricks, you won't be convinced if you win). The two places I just mentioned are indestructible and painful at best. Remember, don't be timid.
The best way is to sit down and talk at the cold drink bar first. If we can solve the misunderstanding, we don't have to do it. Remember, we don't make trouble, but we are never afraid of things.