First, return the cable to Best Buy. You paid WAY too much.
Second, take a few photos of your setup and of any additional cabling which may be run between the TV and equipment locations. This can help us figure out a solution for you.
In reality, people love to say "Just use the old cable to pull a new one." It never works. Or almost never works. Cable pulls, especially those installed pre-drywall, use small holes that the cable barely fits through and then the cable goes through any number of 'convenient' turns rather than a nice smooth, wide open cable path.
Typically cables, when installed at the time of construction, are put in by electricians or inexperienced AV guys who care NOTHING about replacing the cable, having a back up plan, or future-proofing in any way.
Coax is a very common cable to pull behind a TV, where it is most often completely useless to anyone. If any extra cables you have don't go to the location where your equipment is, what does it matter anyway?
At the end of all of this, the cable you broke, COULD be spliced back into place if you take your time and carefully put it all back together. It's a fairly insane process and has a high likelihood of failure. But, I've seen it done before by someone who did it and used the cable for several years with 1080p content.
But, in reality, you will want to take a few photos of the space, post it, and get ready to cut some drywall and open things up so you can replace that cable.