AITA for overreacting in some peoples opinion?

I, 15F, dyed my hair purple on the night before my 15th birthday. Loved it, whole head, etc. I go into a YMCA because I swim with my dad there, and walk by this elderly lady (she looks to be about 70-80) and she looks at me and this is the conversation:

Lady: Is your hair dyed purple?
Me: Yeah it is! I did it for my birthday
Lady: You know dyed hair leads to that mental disease, right!
Me: What mental disease *(fully expecting her to say schizophrenia*)
Lady: That rainbow disease, LGBTQ+.
Me: I have a girlfriend