There’s an unwritten rule in society. That you should always be on your family’s side of an argument, divorce, breakup, fight or anything else that involves two sides.

But what if you knew your family member was in the wrong?

Ever heard the saying, ‘Mind your own beeswax’? Well, when your sibling is in the wrong, we’d recommend staying far far away from those bees and their wax. But a Reddit user, by the name of brotherconfessedchea isn’t so sure.

She has taken to the internet to ask us intelligent online folk what to do in her… sticky situation. Her brother is currently going through a divorce, but he just confessed to his sister that he has had an affair…

“My brother and his wife are going through a divorce. They’ve been married for five years and have two kids. However, during the past year, things have been absolutely sh*t for them. They’re marriage started breaking down, they were always fighting and shouting,” the Reddit user wrote.

“Recently they announced they were getting a divorce, and are going through divorce proceedings currently. From the way things seem, it looks like they will split assets 50/50 and have shared custody over the children,” she continued.

It all sounds very amicable. Concious uncoupling kind of vibe. Nice neatly wrapped divorce story. (As far as divorce stories go). But then she and her brother decided to get alcohol involved. We all know that's never going to leave things uncomplicated and mess free...

After a night out drinking at the pub, the sister and brother walked home and crashed on the couch. The Reddit user believes her brother was slightly more intoxicated than she was. They started to talk about deep stuff. You know the kind of drunk where it goes beyond funny antics to 'how we came to be in this world' type conversation.

"I don't normally talk about this sort of stuff with him all that much in depth, but this was the biggest heart to heart we've had in a while. We talked about both our relationships [and about] how his marriage has broken down," she wrote. "During it he confessed to me that he'd been having an ongoing affair during the last year, while the marriage was already in shambles. This was going on for a while before they announced the divorce, and his wife never knew."

The brother apologised for his word vomit the next day and told his sister that he shouldn't have said anything because he didn't want to burden her with that information. Alas, it was too late.

Now she's in a pickle.

Her moral compass tells her that his wife has a right to know. But she also knows that it will affect the court proceedings and big things, like the custody of his children. While she doesn't want her brother to lose custody of his children (who he loves very much), morally she believes the fair thing to do is let the wife know.

"But I really don't want to do that; I don't want to negatively affect my brother's case and I don't want to destroy my relationship with him. I mean sure his wife has a right to know and it would be fair of her to know, but to tell the truth, I never really liked her," she said.

Ultimately the Reddit user admits that she never liked her brother's wife, and doesn't feel like she owes her anything. But her ethics are tugging at her.

"I'm not sure what I should do with the information, should I come forward with it, or just take it to the grave and pretend like I never found out?" she questioned.

What do you think she should do?