YoahiShe wasn't using the word "lesbian" in a derogatory way, at least if she was, the screenshot you provided didn't show enough proof on it. She just stated a lesbian woman had messaged her.
ThePowerOfSixReferring to a human being as a lesbian is pretty offending.
If I were to come out, and someone would refer to me as a g*y dude, I'd be insulted, and offended. You could just call me by name, why add the unneeded detail to your sentence. ???
https://www.google.ae/search?q=gay+meaning&ie=utf-8&oe=utf-8&client=firefox-b-ab&gfe_rd=cr&dcr=0&ei=0FKwWYGZKZuq4gSVwaOQCQ
"This lesbo msged me"
Is just like
"this gay person msged me"
SOOOO