My best friend is unfaithful: should i tell her husband?

Are you morally obligated to divulge your friends affair, or is that “tattling?”
You love your best friend, but you also want to stand up for what’s right. One day you either catch them in a moment with someone who isn’t their spouse, or they confide in you that they’ve been seeing someone else.
You want your friend to know that you are their confidant, but you also believe that what they’re doing is wrong and you don’t want to be pulled into their personal mess.
So what exactly should you do if your BFF is having an affair? This can be a big concern for your friendship as well as your personal peace of mind.
If you were in the same situation, it’s likely that you would want someone to tell you about it rather than finding out by catching your partner in the act. And while it’s a huge dilemma for you, you know that of course, your friend doesn’t want you spilling the beans about it to their partner.
Should you tell their spouse and risk alienating or even potentially losing your friend, or should you keep things quiet in order to preserve your relationship — even if you know that what they’re doing is wrong?
There’s also the other option where you can prompt them to tell their spouse the truth, but again, this might bother you since you feel like you’re stuck in a problem that you shouldn’t be involved in. And there is always the concern at the back of your mind that no matter what you do, you might lose your friend.
Overall, this is a big, scary mess, and it can eventually be ruinous for a friendship if nothing is done about it. Or ruinous for their marriage, too.
But don’t focus on those problems. Relationship expert John Gray has some advice for this sticky situation and a way for you to ease your feelings of guilt or panic.
Whether or not you should tell her husband or partner is dependent on many variables, says Gray. He also talks in the video above about how you can learn to navigate these variables so you can make the right choice in the end.
When you’re stuck in a situation like this, it can eat at you and upset the balance and peace in your life. But you shouldn’t drive yourself crazy with the decision that your friend has made, even if you feel like you’re unfairly stuck in the middle of it.
Whether this happened because your friend told you directly or you found out by mistake, it doesn’t change the fact that you are now in what feels like a completely unwinnable situation.