Children are smart, and can bounce back if they get out of a nasty situation and get the help they need, but sticking around in this situation is teaching your toddler that these behaviors are okay.
Children learn about relationships from their parents, and are prone to repeating them. For the sake of your toddler, you need to provide a safe and stable home, so she can learn good values.
Your unborn baby is already at risk, due to your wife's alcoholism. I sincerely hope and pray that she'll be safe and healthy - the more your wife drinks, however, the more that chance decreases - drastically!
There are some difficult decisions you need to make.
I would just like to point out that your wife is an adult, and should be able to take care of herself.
Children, on the other hand, rely upon someone to take care of them. Your wife is not reliable, so you need to find some sort of care that is reliable - for the sake of your unborn baby, and before the courts find it for you.