Feeling so defeated

I've been exactly there before, and the feeling of defeat is huge but is sounds like you learned from it, which is key.
When I've had rides like that I've made sure I get out within the next couple of days for a route that I know I can take on and give myself a success ride to remind myself why I love cycling and to remind myself that I CAN do it.
I was defeated at a ride like that a few months ago and was going back to the same town for TDC and was a little worked up about being able to get through it. I got myself a good riding partner, made sure I ate and drank throughout the ride, and stayed positive. I rocked the ride have a lot more confidence now.
Sometimes it's the day, sometimes it's mechanics, weather, lack of food, lack of support- all of these things can knock you down. You rock for getting 36 miles in those hills!