"listen to thier voices"...they can take their voices to hell.
They want to be treated with respect, but can't respect your art as it is.
Don't even apologize to them or explain, it'll only make them more audacious. You would be better off as an artist without "fans" like that.
Reality is if you're going to have black characters and black culture in your creation, you're going to attract black fans and you need to learn how to treat those fans and black people in general with respect and listen to their voices