The pregnancy is a sticky point and I agree, hard to walk away from that.
My list would look like this.
1) You check into inpatient rehab and stay there until baby is born. That is what - 60 days or so?
Don't even try to guess if she really needs that or not. Any woman that hides/drinks vodka when pregnant needs it. If her story is true and that is the first drink in 8mos and she felt so guilty she puked it up - then she really needs it because she drank it even though she had the alarms going off. She can't control it. From what you shared I find it hard to believe that her first drink wasn't several weeks ago.
2) When she gets out, she works her recovery, you work yours. If you slip - I split and baby stays with me. Try not to micromanage the recovery. Go to marriage counseling if needed.
I mean - I talk a tough talk and all. I should say that is what I would want my plan, and my actions, to look like.
She might not agree to #1 (probably won't). Is there insurance or money for that? If she doesn't I'd consult a lawyer and find out exactly what you can and can't do right now, and when the baby is born.
I start with rehab because I can not imagine any daily contract, police work, big brother tactic, that you and her can engage in that will not completely destroy your relationship. It is not healthy for either of you. Yet there is a baby to think of.
I'm glad you are going to go to alanon.
Take care and keep posting!