How to cope with being cheated on?

It’s strange when you come to know that you have been cheated on by someone, it happens mostly in boyfriend/girlfriend relationships, where you have high expectations and they broke into pieces when you realize that you have been cheated on.

5. Understand The feelings of Crashing Down

I understand that feelings of crashing down, as once it happened to my friend and I was the one who witnessed this, she have been in a relationship with a boy for three years, apparently it seemed that they both love each other, but later on, from some other resources she came to know that her boyfriend is in relationship with some other girl of his town, that was something hard to belief, but when my friend found that she was just shocked, she was crying hard and was numbed, as its difficult to realize the fact that the person you loved for three years cheated you, he was cheating/lying throughout this journey.