If my spouse passed away, can I legally terminate my lease?

Sorry to hear about your spouse.

Unfortunately, death won't terminate the lease.  If the landlord doesn't let you out of the lease, you will remain liable for the rent for the balance of the term of the lease or until the place is re-rented.  Once the place is re-rented, your obligation to pay rent ends.  The landlord has to mitigate (minimize) damages by not allowing the place to remain vacant for the remaining eleven months of your lease.  The landlord has to make reasonable efforts to re-rent the place by finding another tenant.  If the landlord does not make reasonable efforts to find another tenant, the landlord's damages (the amount of compensation the landlord is claiming you owe) will be reduced accordingly.  Reasonable efforts on the part of the landlord to find another tenant will be determined by what other landlords in the area are doing to attract tenants; for example, posting a sign advertising the vacancy on the premises or advertising the rental in the newspaper, online or in a local rental guide, etc.

If the landlord re-rents the place, as mentioned above, your obligation to pay rent ends; however, if the new tenant is paying less rent than you were paying, you would remain liable for the difference in rent for the balance of the term of your lease.  The landlord has to have a valid reason such as market conditions for charging the new tenant less rent.  If the landlord does not have a valid reason for charging lower rent to the new tenant, the landlord has failed to mitigate damages and the landlord's damages will be reduced accordingly.