I'm so sorry you had this experience, but yours is definitely why I do not like seeing teens so involved in fandom and especially reading/writing/taking part in the adult fandom spaces of yaoi, m/m fic and art, etc. I wrote in another thread here that I'm an old fandom dinosaur, back from the days where access to fannish m/m fic and art - and also m/f explicit stuff - was VERY tightly controlled. You couldn't buy such fanzines or art at a convention or via the mail without showing a copy of your driver's license/other ID to prove you were over 18 or 21. Publishers were VERY concerned about getting in legal trouble for potentially "distributing pornography to minors". Anyone found to be underage was kicked off slash mailing lists, or not approved for membership to protected web archives.

In contrast, today? Everything is just OUT THERE online for all to see and read on tumblr, the big fic archives, twitter, etc (and if anything, teenagers yell at older fen that we should go away, that fandom is just for young people.) To me it's much like how porn can be so damaging to young minds by warping expectations of real life relationships and sex. Instead of learning to cope with the changes and challenges one goes through during puberty and the teen years, kids are escaping into fandom, projecting on characters (who aren't always or necessarily good role models), and deciding that if they "identify" with a male character that means they must be trans. It's very disturbing and sad to me.