Do file reviews! It's easy to get lost in the 'I didn't get in' blues, but speaking with the school and finding out what you can improve (and what is already really strong!) gives a little emotional relief. You have direction (you KNOW what you need to work on, you're not just guessing) and you have a little confidence bump (you KNOW what the school liked and why they interviewed you, and with all your insider knowledge from this cycle you're in a great position to prepare for next year).
Take a deep breath. Rejection sucks but it's not the end, it doesn't mean you won't be accepted next time or by another school, it doesn't mean you'll never be a vet. Come up with a plan for next year - where will you shadow/volunteer? etc, and take some time to relax. Read some books you love, go have an adventure outdoors, play with a dog. It'll be okay, I promise.