This happened to me as well but I was the one being abused she just wanted to play around and I didn't know it was wrong as an adult was also doing it to me but it didn't just happened with her, there was also this boy he used to play these 'games' with the girls at my childminders (usually just me and her) sometimes it went further, I think I was the only one he went further with though.
I remember going home and then telling my mum what happened - I didn't think it was wrong - she didn't really say anything to me but then the next day he ignored gave me these looks like I was a peasant or something and like 'what the hell did you do?'. It was because of that that I never told about the other things that happened.