When i feel i was unjustly treated, i tend to overreact and become angry and say things i will regret saying. how do i solve this? is this a disorder?

Injustice: No one likes injustice but we live in a partially unjust world. Managing our emotions prevents a lot of problems downstream. There is constructive and distructive use of anger. Perhaps a clinical psychologist can help you learn some strategies that will prevent problems while dealing w/the difficult realities of life. Peace and good health.