I would make new friends and wouldn't talk to him/her.

thank you for sharing this question with me.
first i would like to find out if she has her own difficulties, i would rather to believe that! second, try to think about myself, did i do something hurt her even i didn't mean. The last but not the least, think carefully: does she deserve my friend, will i forgive her and give her another chance to be a friend again. sometimes it depends.
i think everyone is not perfect. It is better to have more friends than enemies.

I should't care it

Hmmm if he/she a true friend and it depends what he/she do....i will be angry...dont talk with him/her days maybe weeks...start to think about it...and decide if i will give a second chance...

but until today i ever give a second chance...a real friendship is it worth...

ennn.i will sad

Well, this is a popular problem. In my opinion, i can consider him or her why cheat me behind my back, if he or she has reasonable reasons, i can forgive him or her. However, if he or she cheats
me on purpuse, i will have never forgive him or her.

it's hard to say~~i would be very sad when i know that~~maybe i will ignore her/him for a while

must give him or her a chance to clerify why he/she do so and if you think that he/she is falty throughout him or her out of ur mind and be happy with urself
coz he/she have no right to distrub your life

I will not talk to he(she) anymore.

First , I'll make out why he/she cheat me. Whether he/she has something hard. second , I'll think about myself. Have I do something that make him/her not happy?If I did , I'll talk with him/her.If no problem on the two aspects, I'll leave him/her.

simple- give the great punch to that #$%#@@ person (not suitable to call *friend* again).....
hehe..kidding only..
just forget about #$@#@... life must go on..and maybe u can learn from this and be more careful to choose a REAL GOOD friend (like me..hehe!!)..
lets bygone be bygone...

Mm....Maybe I will tell him/her that I'm not that people she chat...

if i realize that s/he cheats behind my back, than s/he can not be my friend anymore..

Dump them. They're not worth it. You don't have to waste your time with them.

Quit that friendship, it is not real. It is true there are times that a person deserves a second chance but how can you trust after a lie, right? It may hurt you a lot; it will hurt you more if you keep trying without results. This kind of lessons teach you and grow. Sorry, the sentiment if horrible but that is life and welcome to it!!!! And get another better friends!!! Have a wonderful weekend