Cheating

What would you do if you got cheated on?
How would you act?
How could you forgive them?
Do you give them a second chance?
What would you do?
I know that saying 'once a cheater always a cheater' but does anyone believe that?

So I know someone that has cheated on her boyfriend. So at first I thought I should tell him because it is going to come out one way or another, better sooner than later. But someone else was going to tell and he thought about it and decided no he wasn't going to tell. There are two ways to tell people things, first out of pure consern and second out of pure in your face. I think that i could tell him in the first way but i think since this sitation doesn't concern me that i will just let sleeping dogs lay. Sorry!