I don't know if it was abuse/COCSA or not...

When i was about 12-13 years old, me and my twinsister used to hang out a lot with the girl that lived next door. She was a few years older (she was 16 i believe) and i looked up to her a lot. I thought she was cool and loved that she wanted to play with us. She would sometimes babysit when our parents were away. So overall we had a pretty good relationship i guess. One time, we (me and my twinsister) were sleeping over at the neighbours and sleeping in the girl's room together. Normally that would just be the three of us, but this time for some reason her brother and his best friend were also sleeping in the same room. Both of the guys were about 17 years old. It started out alright but at some point (either the girl or the boys, i don't remember) suggested playing a game. I didn't really know much about sex at that time, but what they suggested as a game was to have oral sex with the guys. The neighbour girl took me and my sister to a seperate room for a bit, and explained what oral sex was and had us sort of "practice" that on a pencil for a bit. After that we returned to the girl's bedroom. At this point, i don't remember much of what happened (if anything more happened), i just remember at some point being upset and crying. I keep struggling to deal with this memory and often it doesn't even feel valid to call it abuse or even trauma. But i know i was very uncomfortable and overwhelmed. I don't know if what happened counts as COCSA. I recently just learned about this word so. It's all very confusing, but whenever i think about that memory now, i feel very uncomfortable and anxious.