Sexually abused by another girl!

I'm 18 now and I can't get this off my mind! I think I'm realising/rembering that when I was about 6 or 7, there was a girl (who might have been 14 at the time) she lived in my street... I remember she slept over one time (we put the couches together and made it into one big bed, just as kids do, would have been just a harmless sleep over) all I remember is her kissing me, she pulled down my pants and put herself up against me... she proceeded to tell me "this is how people make babies" and then stopped! I remember feeling confused, but I didn't think much of it! I have always had this in the back of my head, but I was too young to process what happened! I know you may be thinking "how could you just forget this" ... I don't even know myself!!! I must have just blocked it out!

When I was 15 I was sexually abused by one of my male best friends (no longer friends obviously) he forced me to do something I didn't want to do while I was drunk and half asleep... I think because of this I haven't wanted to face acknowledging what happened when I was 6/7... it's all been a bit much to handle!

 Can anyone give me some advice?? ***UPDATE*** I Haven't told my mum, do you think I should? I don't know what to do!