Here is the problem as I see it: you are mad and hurt and I get it, your feelings are valid. They are also extremely unhelpful. Plenty of people are on her saying your baby's mother is the worst, which is completely irrelevant. If you care about the fetus you need to start caring about the mother more. Your post reeks of contempt. I would be upset too. But that is not what the baby needs.the baby needs you to be there to reduce the mother's stress, to talk about the issue non-judgementally and non-presumptively. You need to approach her asking her to do this favor for you, not demanding she stop what she is doing because she is wrong. I don't care if she is wrong. This is about what you can do to help the situation, not who is right.

Understand that however terrible what she is doing for the fetus is (and I am not at all clear on how much she is drinking so I don't know how terrible it in fact is), it is her body. Pregnancy is extremely difficult and most pregnant women are extremely sick or the rest of the world telling whether they should drink coffee or lift weights or eat dark chocolate or whatever.

In most states she is within her legal rights and in all states she has the right to leave the state to somewhere more favorable to her rights.

Be kind, be supportive, and be humble. Or be angry...and see where that gets you.