I know this can be super scary but actively doing something about it does help.while you're waiting maybe you should look into what you're facing. With regard to the radiation, chemo, and surgery...there are a lot of posts and Information here by members who've already been through it.

Am I to understand that they are starting you on rads and chemo - then operating? A few days later? That's pretty unusual as the protocol is usually surgery - healing time, Then radiation and chemo, based on your pathology results. Are you having a neck dissection? Have they talked to you about a feeding tube? 60- 70 percent is a lot, but there are people here who've had total glossectomies and gone on to do very well, they can speak, and eat no problem. Depending on how quickly you heal it may take some time but you can do it.

When my tumor was still there it was fairly large I had about a third of my tongue removed - and rebuilt- I assume hey are doing the same for you... Anyway - the entire side of my tongue was red and very sore so I know he feeling!
Good luck - try not to freak out. You will get through this!