This has sadly happened to me... Back in middle school, I began to cosplay. Many of my friends noticed that I have been interested in cosplaying and they thought it was a cool hobby.
I had this one friend (now ex) who thought she was like Queen of Everything, and took violence to resolve everything. She cosplays but when she found out I was planning on cosplaying as Lenalee Lee from D.Gray-Man, she was furious since she always cosplays as her. She confronts me one day saying, "You can't cosplay as her. One, you're short (5'2). Two, you don't look like her. Three, I honestly think you're going to do a terrible job cosplaying as her because I have been cosplaying longer than you have. Noobs like you should stick to noob cosplays". She later slaps me really hard with her musical binders and tells me to stop cosplaying, then walks home. She broke my glasses and I had a slash mark on my face which I believed was from the paper and plastic inside the binder... (Thankfully, I had a pair of contact lenses so I wasn't worried about getting my glasses fixed quickly)
My friends noticed the mark and I told them what happened. They confronted her and told her to stop all this cosplay drama just for attention (that was honestly what she was aiming for). She calmed down but she still finds the fact that I cosplay as male characters is unacceptable.
We haven't seen each other for a while now but she can't tell me what I can or can't do when it comes to cosplaying as characters I love.
Chrome Dokuro [Katekyo Hitman REBORN!]
Rin [Togainu no Chi]
Lucina [Fire Emblem Awakening]