First, don't panic. If you're a minor, it's important to have an honest conversation with your mom about why you were reading it. Maybe it was out of curiosity. Assure her that you understand it might not be appropriate content for your age. For example, you could say 'Mom, I know this was wrong, I was just curious, but I won't do it again.'
Tell her it was for a creative writing class or a writing exercise with a very specific purpose. For instance, you could say 'Mom, I'm doing a writing assignment where we have to explore different types of stories, and this was just an exercise, not something I'm into personally.'
No way. This kind of story is not something that should be spread around. Family relationships are based on respect and trust, and sharing such a story violates that. It's a private matter that should stay within the family.
If 'fum' was something like being in a fum (assuming it's a made - up state of being), I might have been startled when mom saw me. I could have frozen in place, not knowing how she would react to me being in this state.
Yes, it's completely normal to feel shocked. Seeing something so private about your mom is unexpected and goes against the typical boundaries of a parent - child relationship.
Sex education from a mom can be really beneficial. Moms can explain the concept of reproduction in a simple way. For instance, how a baby is made. It involves a sperm from the father and an egg from the mother. Also, moms can talk about the importance of healthy relationships and boundaries in relationships. This helps kids grow up with a healthy understanding of the opposite sex.
Another possibility could be in a more metaphorical sense. Maybe you had an idea or a plan that your mom could tell you were about to execute. Like you were planning to bake a cake without telling her, but she could see from your actions that you were going to start baking soon.
Well, it's a really tough spot. If you're uncomfortable, you might also consider talking to another trusted adult, like a relative or family friend. They can give you advice on how to handle it and may be able to help you understand the situation better. But always approach the conversation with respect and caution.