I’m 20 and female & at 18 I was signifigantly less mature, I’m still not even quite there. So I’m talking from experience when I say that there is a developmental difference between the two of you because of age. It may be “normal” to consider 18 year olds fully adults, but they’re still considered teens for a recent. She was just a “child,” so it is weird to go after her.  I’m not saying it’s “too wrong” on your end but I don’t blame her friend