I am sorry to disappoint you with my answer. There is NO easy way to stop all negative and aggressive emotions from flaring up. I am speaking from my personal experience. Different people have different tendencies and characteristics, mostly carried forward from their past kamma. As such these are very strong traits which are very difficult to change. If one is fortunate to carry positive and amiable traits, one faces less problem and would be most probably a very likeable and successful person. On the other hand, if one carries negative and obnoxious traits, then one is in trouble for the rest of one's life.
The immediate defence is to learn from mistakes and to acknowledge them. Then we try again. For long term strategy, Buddhist meditation is the answer. We have to cultivate good habits in order to rid the bad ones. If we can successfully train our mind to be constantly mindful of our thoughts and actions, then we can control the situation. When negative or hateful thoughts or reactions surface, we will have the presence of mind to check our reactions, and respond skilfully and wisely.
The other approach is to tell ourselves that negative thoughts are harmful to our nervous systems. If we choose to prolong this mental poisoning, then we ourselves, are to suffer and not the other parties. If we are wise, then we will take steps to check our negative emotions.
Below is the recitation that I used to recite most mornings upon waking up. It is from the famous "motivation Guru (teacher)" Napoleon Hill, which I quote:
"Until I've learned to be tolerant with those who do not always agree with me-- Until I've cultivated the habit of saying some kind words of those whom I do not admire--Until I've formed the habit of looking for the good instead of the bad thare is in others; I will be neither successful nor happy. For every act or thought that I release modifies my own character in exact conformity with the nature of the act or thought. I cannot release a thought without first implanting the sum and substance and nature of it in my own subconscious mind, there to become a part and parcel of my own character. This is why I cannot afford to hate or envy or strike back at another person."
See? Universal truths have no boundary. I am sure Hill is no Buddhist, but he had wisdom to see the truth!
Have peace: from justinchoo :-)