Non-violent Communication' by Marshall B Rosenberg. Reading it was a 'light-bulb moment'. Once you understand what he's saying, it's obvious, but it can take a while to understand the concept because it is so alien from the way most of us have been brought up to think.
The basic message is that we all have needs and these needs are perfectly valid.
However, for society to work well we need to balance our needs with the needs of others. When our needs aren't met we often have a negative reaction. This can take the form of frustration, disappointment, discouragement, fear, anger or depression etc. Negative emotions don't help us to get on so well with other people as a rule. Our negative emotions are a result of not getting our needs met, and they are often not met because we have not communicated them properly.
The book shows us how to communicate our needs effectively as well as how to hear the needs of others. For instance, a woman who is lonely and fed up because her husband works late, or goes to the pub after dinner, might say, "You don't love me", or even, "I wish you didn't spend so much time doing x or y". The first statement might make her husband feel defensive and cause an argument, the second might result in him doing something else, but not spending more time with her. So she would do better to tell him she is feeling lonely and unhappy because she doesn't see him as much as she would like and it would really please her if he could spend more time with her.
The husband might then respond that his needs are being met by doing what he is doing, but for a healthier relationship husband and wife could then sit down and discuss whether they would both be happy with some kind of compromise, such as she would expect a less extravagant lifestyle in return for seeing more of her husband, or out of love for his wife he would buy less of the latest gadgets so that he wouldn't need to work so long. It might sometimes be possible to find other ways for people's needs to be met.
You really need to read the book, and probably a few times over, to immerse yourself in these ideas and let them permeate your thinking. I would recommend it highly for it's potential to transform all your relationships, including the one with yourself.
I'm sure this way of looking at things can help us all to feel less aggression and other negative feelings.