If it's a story about a pet cat (as 'pussy' can refer to a cat), it's quite normal for friends to like an interesting story. Pets often make for great storytelling topics.
Another option could be 'Sister and Best Friend's Heartwarming Bond' which emphasizes the strong connection between sisters and their friends in a non - offensive and family - friendly way. These types of stories can be inspiring and show the beauty of friendship and sisterhood.
If it's an appropriate and positive story, you could continue sharing similar positive experiences with them. But if it makes you uncomfortable, it's okay to let them know that you don't want to talk about it anymore.
This is a very difficult and disturbing situation. You must act quickly and assertively. Start by having a private talk with your mother. Express your extreme discomfort and make it clear that this behavior is unacceptable. At the same time, be there for your girlfriend. Listen to her feelings and offer her all the support she needs. You may also need to consider involving a professional counselor if the situation is too complex to handle on your own.
Definitely not. Such content has no place in a civilized society. It can make people feel uncomfortable and offended. We should promote positive values and stay away from this kind of vulgar content.