Congrats. Glad you didn't punk out on us.
My longest treadmill run was 11 miles. I was training for a half, and it was -5 degrees outside and snowing. I hated it! I do run on treadmills a lot since I travel for work and am in hotels a lot (I now pick my hotels based in the gym), but nothing beats a good long outside run.
As for the pain - rest and ice. It seems simple but it works. Also tell your husband he needs to service you tonight. That makes it better!
Great job, again, and good luck at the race.