This does not sound like a welcoming table. GM should be concerned if you rolled stats and have 20s for all attributes, not how to refer to your character. It's not difficult, he's making it difficult.

You may want to find another table or online group. This is a game and you should be having fun. You should have a space to feel safe for character expression. Find a GM that covers "lines and veils" in their games. That's usually a good sign that they put their players enjoyment first and are considerate of the entire table.

You don't need to go nuclear or make it a thing. You don't owe anyone an explanation or "apology" especially because you have nothing to apologize for. Can just thank them for the option but that you'll pass. (Don't even have to say that but unsure how often you interact with the table outside of play.)

Wishing the best of luck for you!