Wendy,
I think the second diagnosis is harder to hear than the first because you already have an idea of what amount of energy and will power it will take to become cancer free.
So sorry to hear about this.
Hemi or full glossectomy.... That's a tough one. Please be sure you ask as many questions as possible prior to the surgery and have someone around as much as possible during your recovery.
Hope for the best, partial resection, but plan for the worst.
Good Luck