Use this situation as motivation
The best comeback for any heartbreak is self-improvement. Maybe your crush rejected you because they saw you didn't take care of yourself properly or that you didn't have the right relationship qualities, and that is probably your wake-up call.
So, if you choose self-improvement after this, it shouldn't be about proving anything to anyone. It's just a chance for you to work on yourself and that hurt is the perfect source of motivation.
Talk to a friend about it
You should take some time to recalibrate your life but, be careful not to sink into isolation. Your close friends and family are there as your support system and you should open up so you can get the strength you need to move on. Choose someone who you trust and vent if you need to.