This is key. Financial control is also abuse.
@dazzledfrog, you mention the tv was bought with your joint money. Do you have solely a joint bank account? What income do you have? Are you on maternity leave from work? Do you receive child benefit? Are all the bills in his name?
Financial independence is key to personal independence, and certainly to leaving an abusive relationship. If you don’t already, I strongly advise you open, or start using, your own bank account. Don’t tell your DH about it and be careful he can’t find evidence, e.g. bank cards, mail. Any money which is yours should be paid into there, including child benefit. The joint bank account should be for money you each contribute for household costs. Consider seeking advice on claiming UC in your own name on the basis you’re in an abusive relationship, which you need to end.
If you don’t work, start investigating part time job options for once your baby is a year old. Jobs in schools can be helpful, as they allow you to work school hours and have the school holidays off to care for your children, which would be cheaper than childcare for 4 kids. Ask at the children’s school about vacancies and find out if there are any courses you could do to boost your chances of getting a job in a school. Once you’ve had advice on the abuse from Women’s Aid or a local domestic abuse charity, you could tell the school in confidence you’re experiencing abuse and need to get a job to make it easier to be a lone parent.
As long as you’re earning above the household benefit cap threshold (currently £793 a month), you should receive a fair amount in UC to be able to afford rent and bills on your own. As the kids get older and more independent, it should be easier to work more hours, particularly if you can get a job with working from home.
Of course, as you’re married, you’ll be entitled financially, including child maintenance from your DH if the children mainly reside with you, which I’d strongly advise they should, given his anger, frustration with and disinterest in them. But settlements can drag out, so having some financial independence in the meantime should make things easier for you.