YTA. I first went vegetarian when I was 12. My mother told me I had to make my own food, which was basically cereal since I was never taught. I did this for a while until she realized how serious I was about it. She only really would make pasta and nothing of real substance but over time she understood I wasn’t changing and would even tell waiters at restaurants that I was vegetarian. You may not understand, but trust that she knows what she wants & teach her skills that she can use when she is on her own. I have been vegan for 4 years and learned to cook when I left home. I eat healthier now than I ever did. Spend time with her, teach her life skills and be open-minded. You can learn things from her as well. I would be devastated if my parents reacted the same way you have.