I have to agree with coyote on this one.
You set a boundary for your family. (good for you)
Your mom is rebelling against the boundary. (that's one of the things people do who get boundaries they don't like)
I suggest you hold the boundary and *let go* of what your mom does - feel hurt, feel angry, throw a temper tantrum, cry, rage, ignore you, pretend she didn't hear the boundary, give you the silent treatment, say she accepts then brings alcohol anyway, blame you for ruining her life, blame you and say you don't love her, minimize her drinking problem, etc. etc.
All you have to do is keep that boundary loving and firm and be prepared to follow through on consequences if she breaks it.
I admire your courage!
peace