When I was 12 my brother (who was eight) and I started kissing. We would kiss each other flat on the lips and any other way we tried it we found to be gross and didn't really do. We would do this occasionally probably over the course of a couple weeks or so and it was basically limited to this kissing. In one incident I asked him to touch his penis to my vulva and offered to do whatever he wanted to his penis for twice as long, but he refused and so we never did it. In fact at no point did I ever pressure him or force him to do anything and he seemed to enjoy everything he did. I don't remember specifically but I feel that we were both initiating things and that it wasn't just me. The worst thing happened when we somehow decided (I'm not sure who suggested it) that I would put my mouth on his penis. The instant my lips touched his skin I stopped and realized how disgusting and shameful it was to do all of this. After that moment we never did anything of this sort again. I remember thinking his penis was disgusting and I don't think I ever touched it in any other way. I think before I did this with my brother I had kissed a younger friend of mine who was probably 7-9 years old. This was shorter lived and didn't progress as far but she seemed to enjoy it and we would giggle a lot whenever we did it before I finally decided that it was too inappropriate to continue.
After I stopped doing this with my brother I felt nothing but shame and regret over it. Honestly at 12 I wasn't as socially developed as other kids and acted inappropriately quite often (though not in sexual ways.) I think maybe this is why it feels as if I was younger than 12 when this happened and also why I understood that it was wrong for siblings to do this but I didn't so much understand the age difference. I have never felt any other attraction to small children.
I recently told all of this to my boyfriend of 2 years. He was absolutely stunned and didn't know what to make of it. He looked it up and learned that it's not predatory but is still very uncomfortable with the age difference. He thinks that 12 is too old to do this with an 8 year old and that I had too much power in this situation. He's still with me and still loves me and tries to be close to me, but he says he's still very uncomfortable and might leave me in the future if he can't accept it. It's scary enough to know this but what's even scarier is that I feel as though if he did leave me I could never find anyone else who would accept me despite knowing this about me. I am anxious and distraught all the time and can hardly sleep. More than anything I want to know that this is normal and that it doesn't make me predatory or manipulative and that my boyfriend can reasonably accept it.