How do you tell your mom you are going to major in art?

How do you explain to a mother who fully believes in science that you want to pursue a career in the art field? My mumsy thinks that the world revolves around science and has never supported me with my art, she wants me to become a vet, but I don’t want to waste years of my life paying for a career that I wont enjoy. I have tried explaining this to her subtly, and she has already threatened to disown me for good. HELP!