My mother spat in my face over money - need advice

السلام عليكم ورحمة الله وبركاته I'm unmarried and still living at home while I study at university, take a few online courses, and work a part-time job plus some side projects. My mother always tells me not to get involved in housework and to concentrate on my studies and work so it benefits my future, إن شاء الله. Today I came back after studying and hanging out with friends, planning to quickly go to the gym because I have to get up early for work. My mother saw me and started complaining that I'm never around and don't help in the house, even though she herself told me to focus on university. She then said something like, “I wonder how much you'll help me after you finish,” and I said I'll likely be working full-time with possible overtime. That's when she asked about my earnings. She kept pressing, asking “How much do you make?” I asked why she needed to know and told her it wasn't really her business, but she persisted. Then she said, “If you make £300–400 a month, you could give £100 a month to your mother.” I refused and explained that, Islamically, the primary financial responsibility is my father's; if he couldn't, then the responsibility would fall to my brother, not me. I stood by that and then she spat at me and claimed “this is a test.” For context, I pay for a lot myself: car insurance and maintenance, most of my food and toiletries, my gym membership, tuition for private online courses, outings for my younger siblings and occasionally some of their necessities, and more. Even if I earned more, most of it goes toward these expenses. Islamically and culturally, I'm not her wali and I don't have a financial obligation to support my parents unless I were the sole earner, which I'm not - my father works full-time and my brother and mother have part-time work. This isn't the first time she's brought money up. I'm starting to feel less like her daughter and more like an ATM. I'm not sure how to handle this respectfully but firmly, and how to respond if she brings it up again without escalation. Any advice or similar experiences would be appreciated.