I felt in a similar position a few years ago. Life at home was miserable and I was walking on eggshells around my angry husband, as were the children. I had been a stay at home mum for 8 years, having left a good career to raise the children (I loved being a stay at home mum but would not advise my daughter to do the same, I would suggest to her to keep working part time so that she is not financially dependent on a partner) so money was a big worry for me as I had no income other than child benefit and a small amount of tax credits.
I was torn between staying and leaving because of the fear of how I would manage financially and my worry that he would fight for 50/50 shared care (his relationship with the children was pretty bad at that point and I didn't think the children could cope with that). In the end I made the decision to leave the relationship after an incident when our eldest was cowering in his room so scared, as his dad was shouting at him over and over. I had to sort myself out financially first though, I wasn't able to go back to my old career so applied for jobs that fitted in with school hours. I got a job in a school 3 days a week, pay was low but it was a start. When we separated I had enough money coming in (wages, child benefit, child maintenance and I claimed a top up from universal credit) to pay the mortgage & all bills.
I then took a college course 1 day a week to get some extra qualifications to help me get a better job. Since then I have found a full time job with better pay and have been promoted since then. I don't earn a lot but it is enough (I don't enjoy the work at all but that doesn't bother me too much for now).
After the divorce went through the family house was sold and with the equity from that I have been able to buy a home for me and the children. It has been a struggle, the kids still do their clubs etc but I have no money for myself, for holidays, days out etc. If things become more of a struggle financially in the future then they will have to stop going to their activities.
Do you and your husband own a home or rent as that will make a difference to your finances. If you own a home that would need to be sold you would be entitled to a share of the equity from it. If you rent, you would be eligible for help towards rental costs from universal credit. If you only earn a bit above minimum wage you may be eligible for more universal credit than you think. Have you looked at www.entitledto.co.uk for a calculation of what help you could get? If your income is low and you claim universal credit your children would be entitled to free school meals, you might get help with council tax (as well as the 25% single adult discount), you can claim up to 85% of childcare costs back from universal credit if you have childcare costs (my youngest is in primary school so i have to use breakfast club/after school club so that I can work full time and universal credit helps with this cost). There's often lots of extra help out there to help you get on your feet.
Would your husband really want 50/50 shared care of the children? I was very worried about this with my ex but the reality was that he told everyone I was taking his kids away from him, he never saw them etc. but 5 years on all he really wants is 24 hours a fortnight with them and the odd day or two extra in the school holidays. The children's relationship with their dad is much better than it was when we lived with him, and they have pretty much forgotten how bad things were before we split.
Personally I feel I made the right decision, it is incredibly hard financially and in the early days I did wonder if I'd made a mistake. But it has been worth it, the kids are happier, I'm happier and I hope it shows the children that you don't have to put up with being treated badly by a partner.
You are stronger than you realise and whatever option you choose you will get through this.