OP you've had a few flippant posts on this thread which aren't really helpful, but there are also those of us here who have walked in your shoes and understand how fearful you are.
First things first: take stock of where you are.
Housing: are you in rented or owned? If rented (whether private or HA), is the lease in your name only, or have you added him to the lease? If you own, have you added him to the deeds?
Support: Sounds like your family are quite volatile. Is there anyone in the family, perhaps an aunt/uncle or cousin, who is a bit more sensible and could help you both emotionally and practically? Apart from your family, is there any friends that you're close to and you feel would be supportive? Even if he's isolated you from your friends, you can still reach out (safely, without his knowledge.) If I had a friend who had fallen off the face of the earth when she got a new partner and then got a message from her saying "please help me" I would without doubt be there.
Aside from family and friends, do you have a HV? When s/he visits, is your abuser present or are you normally alone? If alone, please consider confiding in the HV, they are trained in how to deal with domestic abuse.
Also: GP. Have you ever needed medical treatment after he's hit you? Or does he make sure he only hits the parts that hurt but don't bruise? Even if you haven't needed physical medical attention, you for sure need mental health support. Make an appointment with your GP and ask for help. Again GPs are trained in dealing with DV. If you can't face saying anything, just pull this thread up on your phone and ask GP to read it.
Womens Aid: Someone has already signposted this, but please do call them. They are there to help you. They can advise on housing, legal, childcare, police and all sorts of things. Most importantly, they can let you know that you deserve better than this.
Finances: Do you have a job that you're on maternity leave from? If you returned to work full time tomorrow could you cope financially? Is there anyone you'd trust in your family to do childcare, or could you handle the cost of a childminder? Would your salary cover that - if not, could you get child tax credits (or whatever they're called now) to offset the difference? If that wouldn't work could you claim income support as your child is below school age? {again - my knowledge is out of date and it wouldn't surprise me to hear that the DWP now require every new mother to be back at work within 6 weeks but let me shut the fuck up about politics)
Don't even think about maintenance for now - he's giving you fuck all already so it's hardly a loss. You can choose to pursue that at a later date, or not bother.
OP you are worth so much more than this, and so is your daughter. I wish I could give you a great big hug. You deserve to live your life without fear of being caused pain. I truly hope you can recognise your own value as a human being.