How does anger come?
“It's never what people do that make us angry; it's what we tell ourselves about what they did” by Marshall Rosenberg.
I am sure that you have to stop comparing yourself with others (especially those who have achieved more) and constantly concentrating on what you do not have. Think on what you do have and maybe sometimes compare yourself to those who have less. This will give you a sense of gratitude and gratitude will take away discontent that is cause by ever present unhappiness caused by concentration on what is missing in your life. Learn to enjoy what you have. Your value does not depend on what you have or don’t have. You were created by God Almighty according to His image and likeness. That’s the measure of your value. Don’t you use other measures. They will only make you feel inferior and unhappy, and also angry.
Your attitude to what happens is more important than things which happen to you. Your reaction is the key. As I said, things that you have not planned happen and this can make you angry. But it only makes you angry if you see that as a bad thing. It is not bad in itself. You can find a way out of it. Try to see something good about it. Maybe it will turn out better than you have planned. Even if it won’t, it should not make you unhappy. Allow modifications to your plans or even a complete failure of them. Learn to react positively to it and you will learn how to get rid of your dissatisfaction.
If you heard and keep hearing a lot of negative words about yourself, you probably need to change your friends and find those that would be optimists and could say you something good daily. I would also encourage you read Bible daily. You will find out how great God’s love for you is. This will naturally take away your feeling of bitterness. His love gives deep inner satisfaction and irritation goes away unnoticed.
I hope you found something useful about anger management.
Anger on Wikipedia