Hopefully your recover is going well now. 70km plus a parkrun is still a great achievement! Your story reminds me of the only time I tried going that far. Not an official race but in covid I did 100km from my house 4x25km laps. It got terrible after 75km on my last loop. I was hoping for 16 hours but it took over 22. It last bit was just a shuffle having to rest every k. I changed my course to avoid hills. My only motivation was I would never have to do it again if I could finish. Never again but just maybe if like you said I could do better training before hand.
!BEER