When you are in the midst of an upsetting situation, can you simply observe what is happening? Can you stop thinking that someone is insulting and abusing you? Can you forget that you are being treated unfairly and let go of the wish to do something about it?
Don't be abusive. Don't react. Try to realize that the real problem is not what is happening, but how you are reacting to it.
When you see that you are going to react negatively, at this point, pause. Stop talking. Say to your mind, 'No, don't say anything now. You will get a better opportunity to present the whole matter in a more effective way. But now you keep quiet for the time being.'
During this pause, try to think of something positive, something elevating, something sweet, something that you consider unforgettable. Try to recall a pleasant event or memory. Focus all your energies, all your thoughts on that.
If you can do this, you won't be bothered or angered by the ridiculous words and unbearable face of the other person.