I would do that, get another battery and drive it home. The car will last anywhere from 30-60 miles depending on loads (A/C,stereo,etc) so if you don't absolutely need it, don't turn it on! I'm including turn signals and brakes (don't drag them or stop slowly). I know, this makes you a bad driver but getting stuck in the middle of an intersection cos your car died is worse, IMHO. Your alternator is definitely dead.
Your battery is putting out 5 volts because the alternator is not charging it. When you put the boost pack on, it goes to 10 volts because the boost pack is taking over the job of charging it. Obviously, the boost pack does not have the capacity to charge the severely depleted battery so it doesn't go all the way up to 12 volts.
FYI, you may go through more than a few autozone/AAP alternators before you get one that works for more than a few miles. They're well known for not working well. I would recommend a rebuild by a professional alternator/starter rebuild shop.
I've had this happen to my SHO too. I feel your pain, bro. Good luck to you.