Is it normal to have fingered a girl at 10

okay when i was 10 my dad had a girlfriend who had 3 kids the youngest (lets call her jane) was a bit of a to put it delicately SKANK (im serious she went as a hooker for halloween once) now she would come over sometimes and bring her friend and then her friend, her, me and my brother (all of them except me were about 12) would play "nightcrawlers" which was a game where we would go into a super small 4 by 9 room that was next to the laundry romm and the girls would do this thing where they would lie down hold there breath stand up and then we'd turn off the lights and my brother and i would make out with the girls(i was 10 and didnt know exactly what sex was)well one time my brother was in the bathroom after one such session and jane took off her pants pointed at her crotch and said put your fingers here and me not knowing any better did then she said rub and i did until she climaxed months later our parents broke up i haven't seen her since and i would like to know if anyone else has ever been in a similar situation