I truly am sorry you are going through this- and I also truly believe that she put your daughter's life in danger. This could have ended tragically, it is so good you were there, I am chilled to think if she had choked on her vomit, the poor lttle thing.
I would call the police, regardless of any future consequences you may think will happen. Even if she were temporaily taken away, it is better that than neglected and put in danger from her own mother. This child needs protection from the mom and her fuckwit of a sister. The very fact that she doesn't see the seriousness only underscores how incompetent she is as a mother.