thats how i felt. would basically run for 5 min walk for 2 the last 6.2 miles.
i'm proud of myself for finishing but have never hurt more in a race than those last 10k.
Congrats on finishing! That last 10k is brutal. I think my splits were close to yours... Looking good at 20, then implosion for the last part.
Have a cold one, and it may help to walk up stairs backwards.