How do I tell my mom that I write fanfiction?

Very stupid question, I know. But it's been bugging me since I started writing fanfiction on Ao3.

I'm a pretty introverted person, I have been since kindergarten. I keep to myself and some close friends but that's it. My parents, especially my mom, are the complete opposite. They're both extremely social and constantly try to get me to come "out of my shell" (which makes me incredibly uncomfortable).

I started writing fanfiction in April last year on Ao3, and it’s honestly been one of the best things I’ve ever done in my life. I enjoy it and it has improved my English skills and grades quite a lot.

The thing is that I write fanfics on my laptop and have this habit of closing it when someone randomly sits next to me. My mom does this a lot to check up on me and gets upset whenever I close it. I've tried explaining it to her before, but she doesn't seem to understand me. She always asks me what I'm doing and I just tell her that I'm writing. Then she gets more curious and asks if she can read it. She has threatened to open my laptop and check on my fics before like two times. I doubt she'd ever act on it but it gets me extremely paranoid whenever I leave my laptop in my room (even when I do close and shut my laptop down fully).

I don't know why but I'm very ashamed and scared to tell her that I write fanfiction?? My mom has let out interesting comments regarding certain things I've done/have wanted to do in the past (such as attending conventions and buying figures of my favourite characters). She thinks it's weird. So I really don't feel comfortable telling her that I write fanfiction because I don't want to potentially be met with the sme response, but I also don't want her to always nag me and ask if she can see my work.

Does anyone know what I could do? (She’s in her early 50s, if that helps for context.)