My close friend, female, had a husband who was overseas doing a tour of duty. Her (now ex) husband's brother was stationed in the same place as them, but not active duty.

Her husband comes back literally weeks before her husband's brother leaves for a tour of duty.

While his brother is gone he starts cheating on my friend with his brothers wife.

She catches her husband with her sister-in-law.

Problems ensue.

The brother who is at the time in Afghanistan gets an email from my friends then-husband, his brother, letting him know he's banging his wife, and basically they're together now and when he gets back he is the one that needs to find new housing.

Brother in Afghanistan takes this all very well somehow.

During the divorce friends husband moves in with his brothers wife, while the brother is still on a tour of duty.

Friends husband's niece, being very small, thinks he's her dad now. Not her uncle. His own sons basically get cut out of his life. Alongside his wife and most of the family.

Brother comes back from Afghanistan to basically his life in shambles. With some of his family blaming him even.

It's a mess, and gets way crazier too.