Lease Ends 12/31

My business partner and I are having a fight about who has to pay for january rent.

My business partner and I were trying to make a mechanic shop and we, were running it out of a facility that rents to people needing garage space. The lease was 6 months and ends 12/31.

We are both done with the business. My business partner indicated multiple times in December that he was going to continue the shop after I left. Yesterday 12/23 he tells me he isn't.

The garage company says that I am required to give a 30 day notice before leaving. That, the lease immediately reverts to month to month after the lease end date.

For some reason I had assumed from my experience with apartment leases that we could just leave at the end of the lease. (which now I'm wondering if that's true for apartment lesses. I've always given 30 days notice)

If my ex business partner doesn't take over the lease then how at risk am I if we have everything out by 12/31?

The rent is 1450 and deposit was 500. I don't have 1450 to my name....