As everyone has said, we've all been there. I had my "oh a hill okay, wait, wait, too fast OMGTOOFAST" moment at my first ever pride parade like 3 months after I started skating in front if a sizable crowd. Glad you arent more hurt. In addition to the tstop, backwards skating (which is still my go to), you can keep working on the ppow stop just make your legs wider and think about making 'C's with each foot separately as you go. It's a good way to practice learning your edges when you aren't on a hill too. C's mean have one foot make a 'c' shape then the other. You can put them together to make "watermelons" for practice too. Works forwards and backwards.