First, so sorry to hear about your foot. Second, congrats on your achievement and being valedictorian! That's great news and I'm very proud of you for the work and effort you've put into your studies.
Third, the broken foot thing will suck royally but it might also be kinda cool. Have you ever noticed how much extra attention that people with broken bones get? Everyone will want to do stuff for you and spoil you. People will remember what a trooper you are to have a broken foot and do your valedictorian speech. My senior year, our valedictorian, who was one of my best friends, broke his leg (during gym class) as well. As odd as this sounds, it helped some people see him less as the "nerd" they thought he was, and more like everyone else. It was kinda cool to see how it changed his relationships with people. My only piece of advice, don't tell anyone you broke it walking dogs, it takes away the coolness...lol...jk