>>11570922Start with real analysis.
Just kidding, go through a high school math textbook first, then move on to calculus and what would be a physics I course (kinematics, dynamics and classical mechanics). The calculus textbooks
>>11571628 are good, and for physics, I personally recommend Randall Knight. If you feel like you can handle it, you can pick up Linear Algebra too.
Don't hesitate in using complementary material. Khan Academy, The Feynman Lectures, 3Blue1Brown, university lectures on Youtube, they're all very useful.
During the course of your studies, you might end up feeling like you're a retard that won't ever learn anything, but don't let that hold you down. Almost everyone has one of these moments, you see it happening even to MIT, Cambridge and Stanford kids. You'll be fine.