I f***** my daughter's best friend

They're older now, but back then my daughter was in high school just coming around to that age. Was rough being an only parent to a daughter, boys are easy at least. But she yeah had this one friend from school she always brought around and behaved like a pair. Never thought anything of it and why would I? Couple times sure they stayed at each other's houses which I would have thought they were a bit old for that but it wasn't a hassel. One of those nights I was busy on the computer when the friend walked in. Gonna keep it brief but she had this long time crush on me and was seriously going at it to flirt with me and kiss. I didn't mean to, but one moment then the next I'm plowing into her with everything I got. Never could look her straight in the face after that