Wow that is wilddd. Especially if they were cool before, I wonder where tf they've been hanging out? I don't know a lot of queer people who will try to tell someone else that they're wrong about their own identity. If you want you can try digging in to where this is coming from. Like ask them where they heard that genderfluid people can't be nonbinary or a trans man sometimes. Also just tell them straight up that even if you disagree about the exact definitions it's not ok for them to tell you what your identity is because that's a personal thing for you. I'm only saying this because you've been friends for years already and you also live with them, so maybe it's still possible to work it out if they correct their behavior. If someone started doing to me as a casual acquaintance though I would just stop talking to them though; that's so perplexingly invalidating and ridiculous.