Oh.. Changing
I have been thinking a lot about you and I am not sure how to answer. So I will forget the overthinking and just share the ideas that come to my mind reading you:
First and foremost, I am in awe at your strength and abilities. I know I am repeating myself a lot. Having two babies to look after, one a new born is really difficult in itself, even with lots of support. Dealing with your sobriety in danger and the kind of partner you are describing seems an insurmontable mountain to me.
And you are adding that you also study and trying to keep a business afloat!
Listen, no matter how much of an incredible woman you are (and clearly you are exceptional) I don't believe you have superpowers. No wonder you are having temptations and you are at risk of relapsing. I would want to escape all this too. Because it is impossible to do it all. Just impossible.
There are things you cannot control: the crazy hormones controlling a lot of your thoughts and physical fitness even if you cannot see it; you cannot control a newborn sleeping patterns either. You cannot control how physically demanding is to entertain and look after a (not yet) 2 years old and a new born. You cannot control your partner's behaviour.
Things you can control/may be able to control:
1) Can you ask for a deferral regarding your studies? Having a new born must be a good enough reason wherever you are.
2) Do you need that business to survive? Otherwise I will just drop it. Completely. If you can feed yourself and your kids with or without the support of your parents/other resources, I would go for that. Now.
3) When your partner is not there, go to your house and keep all important documents re kids and you in your possession (bank account details/passports/birth certificate/mortgage papers, etc.) Make sure those documents, whatever resources you have are protected and safe with you.
You know how you became clean last time. You said you did it for your daughter. Your daughter is there and has a sibling. You have a double reason now. I am reluctant to remind you this, because it is obvious you already know and you are under unbelievable amount of pressure. I doubt putting more pressure on you will help. Just want to remind you about whatever reasons/techniques helped you become and stay sober the past 2 years.
If the police is involved, you might already be under the radar of social services, etc. It might add stress that you never caused in the first place. Please, stay away from your partner. It is going to be bad news as long as he can't change his ways. You must detach from him emotionally. Your concern is not helping him, even if you believe it does. Did your parents worrying about you helped when you were drinking? You (neither him in fact) need this drama. It can only make it all worse. Stay far away.
Massive virtual hug.