First, understand that emotions as such don't exist. There is a chemical reaction, reaction to environmental change, aggressive behavior. Pure minds are alien emotions, there is only cause and effect.
Develop your own system of priorities. - Select what to you is reasonable as here and now and in the long run. Jumping from long-term to short-term perspective and back will help you save a huge amount of nerves, but so many things that are important now, have no value in the long term, and what will be then, hardly there now. Use this scheme in case of strong stress.
Reason logically. In the pure reason, as already stated above, no emotions. Think whether you will be useful some action? How it will affect your long-term goals? Calculate several steps ahead and determine whether the development exactly the way you want it to be.
If emotions overwhelm you, put yourself in the place of the interlocutor. Think about whose arguments are better, you will listen, to those set out briefly, clearly, and in fact, or a flurry of aggression? Act based on what is most effective. Remember: your goal is the most important thing that you have.
In case you understand that it is not able to cope with emotions, and nothing of the above does not help, get alone and talk with yourself. Say the whole situation and get rid of the emotions you feel.