Those million steps consist of a million small steps you can take one at a time.
My advice would be:
1 Make the statement - for any number of reasons, mainly to get protection and support you need from the appropriate agencies, this may even include a "panic button" style set up in case he comes around being an arse, also because it shows HIM you're serious and if it puts his career at risk then it may just be enough of a warning to prevent him coming around, also because it will mean you can access legal aid for the divorce. It will also show ss you're serious about no longer exposing your children to dv.
2 speak to your local welfare rights office. They are part of your local council, they are sometimes called something else but they basically help with understanding and applying for benefits and other financial and practical support. Ime far better and usually more up to date on knowledge (crucial at the moment as with covid stuff dwp are overwhelmed and the rules are constantly changing)
3 engage with ss. They will help you move forward and may well be able to put you in touch with local domestic abuse organisations and charities. Women's aid are great IF they are available in your area and aren't overwhelmed, they're kinda victims of their own success and sadly DA is so so common they can't possibly support everyone. Ss will know what's available and what's actually useful in your area
4 get that divorce - makes things so much clearer and easier financially, practically and emotionally
I am so sorry you and your children are going through this. I'm a child of DA and I WISH my mother had the strength to divorce him or even had EVER called the police she never did, and as a result his confidence in being able to behave like this got worse and worse. I left home at 17 to escape as did my brother. Sister lasted a few years longer but she is very stubborn.
You are doing the BEST thing for your children as well as yourself by leaving him.
PLEASE also remember
THIS IS NOT YOUR FAULT
and
IT IS NOT YOUR SHAME
it's his.
Current friends are 'mum' friends with perfect lives who just wont get it.
NOBODY has a perfect life, nobody!
Statistically it is EXTREMELY likely at least one of them has been in an abusive relationship or was the child of one.
I used to be a nurse, I had a number of patients assume I too had a "perfect life" due to my appearance/cheery manner at work. When appropriate and called for I informed them of the truth, they were often surprised.
People don't talk about this stuff but it's surprising what comes out of the woodwork when one person discloses.
I had a breakdown some years ago and was brutally honest with some people about my childhood as a result. These were people who I thought we knew each other well, we were close, had "grown up" together. Some were shocked, some were surprised but some admitted they suspected - the ones who said they suspected? Also had unbeknownst to me similar childhoods. There were a lot of tears but also a lot of sort of camaraderie developed. I was surprised how many of my friends (not just those ones) had very similar issues to me, until a therapist pointed out it's not that surprising. Like tends to call to like even if it's not consciously recognised apparently, she was telling me there's even been studies done on this kind of thing.
I knew sod all about benefits when I split from my ex (he wasn't abusive just a chest) as I'd never had reason to claim, it was a learning curve! But you will manage it.
I also raised my dd (now 20) as a single parent for most of her life and while at times it was hard it was easier than if I had tried to parent in an abusive relationship I think. We've had our trials (I am disabled, as is she. Mine car crash, hers genetic, mh issues, low income, ex being a dick...) but you know what? I think it's very much made us who we are and I hope and seem to have raised her to be strong and capable. But we also have had a LOT of great times, carpet picnics, lovely Christmases just the two of us, a shared rather dark sense of humour (when we first moved into my current address a relatively new friend of hers bought us a sign for the flat that reads "we speak 3 languages in this house, Scots, English and sarcasm") and a love of cheesy horror movies and cheesier romcoms
You CAN do this
Wishing you SO much luck 