Hope that given a little time you will see that what you did is indeed a very real achievement, and that regrets matter little, it is what you did that is important.
If it is any help the chap who organises en-to-end here in the UK, a major cyling event on the PD calendar, also felt exhausted this time round. I think he is around your age too, amazing guy.
Cycling has never been a possibility for me, never learned, but I watch what you guys are doing with great interest, and not a little awe! And you do inspire, if you can manage all that then I can get through the day, whatever it brings...
Take it relatively easy (for you) and recuperate a little!
Lindy