A fully charged battery will not freeze until it gets below -70F!
But, what will kill your battery: 1) low acid level, especially for a long period or 2) having it discharge over the winter or 3) Improper charging over the winter. Good batteries do slowly self-discharge, but that rate goes way down the colder it gets. A healthy battery should never come near full discharge over a northern winter.
Check the water levels, charge it fully, disconnect all connections on one terminal, and don't think about it until next spring!
Unloading/loading or improper over-winter charging will cause more problems (to your back, or your battery) than just leaving it alone ever will. If it's dead next year, it was going bad before you put it into storage!
2012 Ford F-150 Eco, Max/Max
Jayco 26.5 RLS, Reese Sidewinder