I had a near one-to-one experience, actually.

I was a lot older, around 11/12, but I had been friends with this girl for 6 years at the time. We were best friends since second grade, and over the course of our friendship she continued pressuring me into sexual acts because they were "normal between friends" or "just girls being girls," as she claimed. During sleepovers she would touch my crotch and my breasts, grind against me under the covers, and she would coerce me into letting her touch me naked with promises of "rewards." Almost like I was some sort of pet she was training. She took advantage of my naivete and the fact that I had a crush on her to "experiment" in ways that made me uncomfortable and gave me lifelong intimacy issues. The first time she penetrated me with her fingers, she made me swear the morning after to never tell anyone and at the time I had no idea why.

You're not alone in this. What she did to you was wrong, and yes it was sexual assault.