Answer based in Theravada Buddhism.
Such situations that you describe here can really get one burning inside. It can make one so angry. The feeling of being poorly treated can also arise.
The nature of these feelings are dark and stormy. They leave a gloomy print on the mind, which is not conducive to either ones practice or ones way of life.
One can choose to see this from the above mentioned angle. One can react to the anger and feed it, by giving it attention and dwelling in it. One can identify with it and take ownership of it, saying that "I am angry" and that "This is my anger" or "This person did this to me". These are examples of how ignorance (avijja) and conceit (mana), makes one see reality from a distorted perspective. Like when horses are made to eat dry grass, by wearing a green eye-glas, making them believe that the dry grass is fresh.
When one reacts to anger and feeds it, it will grow. When one throws gasoline on a bonfire, it will grow. The negative feed-back loop is in effect. The snow-balling is in effect. When unbroken, this loop will only produce more and more anger. If this anger is allowed to persists in the mind over longer periods of time, it will produce responses in the physical body such as "increased respiration, perspiration, rapid heartbeat, head-ache, tensions".
The above, describes how anger develops when not dealt with and how it can affect ones mind and body and ones practice and life. When anger is left unattended, i.e. without mindfulness, then this defilement can operate in the dark. Defilements like to operate in the dark, where one cannot see them. Here they grow and multiply like bacteria or fungi, which also like dark and moist places.
One can also choose to approach this from an insight-meditational perspective.
By observing the anger with mindfulness in the present moment, one can clearly see how unwholesome defilements really are. One can see for oneself what effect they have on the mind and body. By observing the anger with mindfulness, one is dragging the anger out in the light. In the light, it cannot conceil its operation anymore. When observing the anger with an objective and non-interacting approach, the anger cannot grow because it is not being fed anymore. When one is not interacting with conditioned phenomena, they will reveal their true nature for the observer. Their true nature is that they are impermanent (anicca), unsatisfactory (dukkha) and uncontrollable/ungovernable (anatta).
When one is interacting with phenomena, i.e. reacting to them, one will get burnt. Its like picking up a piece of hot charcoal and holding it in ones hand. One is bound to get burned.
Only you can decide what to do in this situation. Only you can make a decision.
You have the Buddha and the Noble Eightfold Path to guide you.
My suggestion is that you use this remarkable oppertunity that you have been given, to develop insight into the nature of reality. You are very lucky, that you are now experiencing this intense anger inside you. Why are you lucky?
Because pain and suffering are great teachers and if you use these teachers correctly, i.e. by observing them with mindfulness in the present moment, with an objective and non-interacting approach, you will see how the defilements affect the mind and body. When seeing how anger makes one burn inside, over and over, one will eventually stop reacting to anger. One has seen for oneself the destructive nature of anger. If you keep observing the anger, you will also see that it is impermanent and that it changes over time. You will see that this anger is not you or yours. How can it be? It arose without your permission and it does not go away, just because one wants it to go away.
In insight-meditation we treat all phenomena the same. A happy feeling is treated in the same way as intense anger, meaning that the anger is not given more or less attention. All objects are treated the same. When observing the anger and aversion towards it arise, then observe the aversion. You can also observe the physical effects of the anger, if they are there.
In short, use this remarkable oppertunity to see for yourself, how conditioned phenomena affects the mind and body. Use this pain and suffering to cultivate insights. We tend to turn away from pain and suffering, yet these are our greatest teachers. If we were happy all the time, then why would anyone work on themselves?
Pain and suffering is what makes us want to change and work with ourselves. Use this oppertunity wisely. A human life is very short. Cultivate as much insight as you can before this life ends.
Lastly, here are some videos from my teacher Ven. Yuttadhammo, on how to deal with anger and pain and suffering.
Now, I have not gone into the antidotes for dealing with anger, such as Metta-meditation, since that would make this answer too long. Just know that anger is one of the 5 hindrances, that blocks one from progressing in meditation. Read about the hindrances and learn how to deal with them. Metta-meditation is mentioned by Ven. Yuttadhammo in one of the above videos.
May you have a fruitful practice my friend. Let me know, if you have any questions to what I wrote.
