My alcoholic mother watching my baby.. agree or disagree ?

My mother over the years has developed a bit of a problem with alcohol.. she drinks at least a 6 pack of beers a night if not more. She claims it doesn't effect her life so it isn't a problem that she does so however she can't go a night without drinking. Earlier today I told her after my baby is born I wouldn't want it sleeping over or staying late at her house while she's drinking. She's so offended and hurt and completely disagrees with this. She still feels she shouldn't have to stop and that it doesn't make her incapable of watching the baby since she doesn't get flat out drunk. Am I wrong ? I can tell in her face she's about to cry. She thinks since my boyfriend doesn't get along with my family too well this is my plan to keep the baby from her and I was planning this all along.. 😔 it's true she doesn't get very drunk but you can notice a difference in her tone, body language and attitude when she drinks. Am I overreacting by not feeling comfortable with this ?