What would you do? An ex boyfriend revealed triumphantly that he had slept with his eldest brother’s girlfriend and then told this brother what a great girl he had, prompting the brother to propose. They are now married. This ex boasted about this to me and my best friend. He went into detail about the two of them being the last people awake at his brother’s villa, and how they played pool for kisses, which ended up being sex on the pool table. The next morning his brother insisted his girlfriend take my ex to Singapore and make sure he has a good time. Apparently they were kicking each other under the table as he said this. They flew to Singapore with the eldest brother’s credit card and apparently “D*cked like rabbits”. My ex then boasted that the eldest brother was their mother’s favourite and he had taken what the eldest brother had. He was extremely pleased with himself and had always been jealous of this brother’s financial success, while he had not been successful himself and had a lot of debt. My best friend immediately condemned this, likening my ex to Hitler. Neither of us has spoken to him since. Does the brother deserve to know? Is it unreasonable to keep it to myself?