Wine?! But seriously just breathe everyone has bad days. As someone very wise said to me “no one ever goes out to fail, but we can’t be perfect all the time” best to put it behind you and move forward tomorrow is a new day. If confidence is lost, as per other comments, drop it back have a fun relaxed day something that’s easy with no pressure then build up again when no stress or pressure.
Definitely do something you enjoy with your horse. Something you two can just kinda kick back and relax with, and not have to worry about judges. After a bad ride with my last horse, I’d take him into the indoor and just play around. Do some desensitization, maybe a little liberty!