Someone has cheated me!!

The first thing i want to say is, I was very depressed today because someone has (past tense) cheated me . I don't know how to express this, but it really was a huge shock for me . A  person who has promised me that he will do one thing for me, now, in the end says "sorry i never promised..." and he is not doing as he promised. 
 I know if anyone wants to be successful it will be very diffcult for to achieve, 
so, I should update my requirements and wish everyone to be happy and in harmony, including myself.

This correction is a little difficult as I am unsure as to the exact meaning of the writer...but i hope i am close to the right interpretation :-)

Someone has cheated on me

Firstly, I want say I was very depressed today because someone has cheated me. I don't know how to express it, but it was a huge shock for me.
The person promised me that he would do one thing for me but in the end, he told me, "Sorry, I never promised this" and he broke his promise.
I know it is difficult to be sucessful (?).
So, I should update my conditions (?) and wish everyone happiness, including myself.

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"i know if one person want to be successful it will be very diffcult for to achieve" -  To be successful at what?

"I should update my conditions" - I am not sure what you mean here. Can you try a different sentence?

^^^ Try to write these 2 sentences again and I can help you correct them. =]

someone cheats me

firstly i want to say i am very depressed today because someone cheats me . i do not know how to say but it is  really a huge attack for me .
the person who has promised me that he will do one thing for me but in the end , he said:sorry i never promised  this and he  gave up .
i know if one person want to be success it will be very diffcult  to achieve .
so, i should update my conditions and wish veryone has a good condition , include myself .