Most high school and college students are unlikely to earn $20k per year and save it to pay for college working part time and during the summer. Many colleges’ financial aid offices assume that students can earn $3k to $5k per year to help pay for college.
Realistically, the biggest way to fund college that students can earn is through merit scholarships, which can be up to full ride. However, merit scholarships are more likely if you aim lower on the prestige / selectivity scale of colleges, since colleges offer them to students who are at the top of the college’s range. Brown and other Ivy League schools do not offer merit scholarships.
You can take $5.5k to $7.5k per year in federal direct loans, but only if your mother is willing to fill in the FAFSA form.
Be realistic, forget about Brown. You would need your father’s cooperation and money to go there, and it is obvious that he won’t give it. And most applicants there do not get admitted in the first place.