Could you tell some terms to express anger politely?
Specifically speaking, when one has done something wrong or has made a mistake... How can I express this with soft words?
It would be nice to see the difference between some words and they degree of anger or frustration towards myself?
Thanks.Sure; for example, when you forget to so something that you had to do...
So you want to express that you are mad at you...

Question

Could you tell some terms to express anger politely?
Specifically speaking, when one has done something wrong or has made a mistake... How can I express this with soft words? 
It would be nice to see the difference between some words and they degree of anger or frustration towards myself? 
Thanks.Sure; for example, when you forget to so something that you had to do...
So you want to express that you are mad at you...

Answer

You might try, "I am so very sorry.  I forgot to X and am very upset with myself for causing you difficulty through my inattention." Or If you are mad at someone else, You forgot to X and that action caused me to feel angry and as though I am unimportant to you."

Those are fairly vague as  answers.  However, without more details it is hard to be more specific.

Answer

Could you give an example? It would help me give more suitable words. :)

Answer

uptight
irritated 
dismayed

Answer

well you can use words of disagreement, like I disagree, Not necessarily to show your point of view or words  to express anger like : I'm not ok with that, I'm up set, This is annoying.