First, immediately interrupt her and express your discomfort. You could say 'Sister, this is really inappropriate. We are family and we should focus on positive and clean conversations.' Then, it might be a good idea to have a conversation about the boundaries of appropriate family communication at a later time, explaining why sex - related topics are not acceptable in this context.
Politely ask them to stop. Say something like 'I don't think this kind of story is appropriate. Let's talk about something else.'
Interrupt them immediately. Politely but firmly let them know that this is not an appropriate topic to discuss.
No. It is completely inappropriate. Such topics are private and not suitable for sharing within a family context. It goes against moral and ethical norms.
One should firmly stop her and tell her that this kind of story is inappropriate. For example, you can say 'This is not a proper topic, please stop.'
One should firmly and clearly express that such talk is unacceptable. Set boundaries and communicate the importance of loyalty in the relationship.
Tell them firmly that they should not be sharing such personal and inappropriate information. If possible, remove the person from the situation where they might continue to spread such stories. Also, it might be a good idea to inform the wife about what has been happening so she can take appropriate action if she wishes.
A good friend should firmly but politely stop the conversation. For example, say 'This topic makes me uncomfortable. Let's talk about something else.'
The sister should report the situation to the authorities. Blackmail is a crime in many places. At the same time, she should surround herself with a support system, such as family and close friends. They can help her stay strong and not be intimidated by the blackmailer. Also, she should avoid any further contact with the blackmailer if possible.
First, turn it off right away. Then, you can consider reaching out to someone you trust, like a friend or family member, to talk about how uncomfortable and wrong it is that you came across such a thing. And make sure not to spread or promote this kind of content in any way.
Politely ask her to stop. Let her know that this kind of conversation makes you uncomfortable. For example, you could say 'I'm not comfortable with this topic, can we talk about something else?'