Wonderful news!
I think you already named your 5FU "Buddy". That's a cute name.
I read somewhere that rinsing with Mylanta helps the mouth sores. That and avoiding caffeine and spicy/acidic foods. My Mom so far, hasn't suffered with any mouth sores, but gets the "bad taste" and simply nothing appeals to her.
Wishing you an uneventful course, and peace, as you reflect on your good news!!!!
Blessings~
Beth