You can find out what your options are with the lease. How much time is left on it? Some landlords are open to changes. Perhaps one of you can move out and get a new roommate? Or sublet?
It all depends on what you want. Do you want to continue to have the noise/drama/madness that is alcoholism in your daily life? You do have choices. There are always choices even if some are not quite what we would normally want.