If you're best friend turned out to be treating a genuinely nice person poorly, would you confront them? Whose side would you take? It's a complicated matter. On one end, you've dedicated a lot to this friendship and know this friend the most. But on the other hand, they are doing something that you are so utterly and strongly against. So what do you do? One woman chose to end the friendship after finding out her best friend was a cheater—she posted to Reddit to share her story. Her guy best fr…