Holy cow!!!!
I think there are other psychological problems in addition to addiction/and alcohol.
Who knows, maybe the baby's lung problem might even be from her drinking/using or whatever she was doing and she still continues.
I cannot imagine what is going through her mind, but it's not concern for her kids. Maybe she figures she can continue on her own destruction and you'll just hire another nanny and she's free of responsibility.
She souns really gone.