Sorry I may have misread the state...but other than NY , the LL most places has duty to mitigate if there is a breech.
Agree you want a lawyer to,clarify your duties under the existing lease.
I am not so sure that one tenant under a joint and several lease can unilaterally get off an existing lease that rolls over momtH to month at the end WO a surrender at which time security and damages if any are squared up...LL and other tenant are free to execute such new lease as they may desire ..and you go your separate way...Now a willing Ll can execute about the same thing by a one sided contract to release OP ...but nothing says LL need do so.
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OP it's entirely possible that you can give Ll a pile of notices but until and unless there is a mutual surrender of the whole you remain exposed if other,person drops the ball?

