Hi Tracey
Lets throw a bit of theory into this.
Transactional analysis describes how when we talk to people we take on one of three roles, parent, adult or child. The theory is, if I talk to someone like a parent, they will react like a child and if I talk to someone like a child then they will react like a parent. However, if I talk to someone like an adult they are most likely to respond as an adult.
Extend this to abusive or threatening behaviour and you will see that responding in a similar aggressive way will only make matters worse whereas if you act calmly with a steady tone of voice, like an adult, the aggressor is more likely to calm down. A measure of assertiveness is also required to enable you to take control of the situation.
I ramble on.

Dave