Hey - it sounds fairly superficial - I believe my surgery was done in a similar fashion to what you will have - my dr. Pioneered a surgery that gives a real time view of the cancer - he's the head of head and neck surgical oncology at princess margaret. 5 cm sounds about the same I had removed - but I guess the depth is the most important factor mine was 2.4x1.4 cm deep. I had a reconstruction. If you are I can't imagine them sending you home. With a reconstruction your tongue will eventually look pretty normal. With out it will be smaller I suppose. It should be fine see how it looks and if someone asks that you are seeing be honest. If they can accept and understand the truth they're not worth being with.
I hear what you're saying re friends - I still haven't told my aunt or best school friend! It's hard. But do email them or even Facebook it. They'll naturally ask questions. Take care!!! And Good luck with the surgery!! Hugs!