Troubling childhood memory, help?

This is hard, because it's embarrassing and I can't remember it all.... I was 4 years old and a girl, a friend, lived next door to me, she was a few years older though, still young and I suppose she was simply curious, she mentioned shed been doing stuff in science.... Anyway, we were in her room and she asked me to get on her bed and let her my bum... This is hard to write..... I wasn't keen but she eventually convinced me with bribery of sweets and dolls so I did as I was told. Now the hard part.... I don't remember exactly what she did, but she had a toy, I mean a doll, it was a plastic dwarf out of snow White- I remember this- it had a green hat.... I remember she was prodding me with it.... I dont remember exactly what she did, but she touched me with it and held my legs apart.... I repeatedly asked her to stop... I remember..... I think I began to cry and her mum came in and shouted at her daughter, I was taken home straightaway..... It scares me.... I keep obsessivley worrying about it, especially recently, I'm 17 now. Could i have aids/HIV from that plastic dwarf toy? Did she... Put it in me? It makes me want to cry now, maybe thats silly.... But it does. I'm terrified of what she did and I can't remember. I feel like I'm not pure..... Like I'm not a virgin..... I'm sorry.. I just don't know..... Any comments please?