Apologies in advance to @Namechangedforobvious - and everyone else here, that this is so incredibly long. I had to get it all out. Anyone except OP should feel free to skip!!
Ok OP - I have read all your posts (but not the entire thread). I am going to short cut here or I will write three pages worth of posts in one extended essay, so I apologise in advance if any of this sounds harsh - it truly is not intended that way. But this man has taken hold of your, clearly extremely highly functioning brain, and so you are not seeing wood for trees…
That being said - I think some advice here, while really well meaning, plays into your understandable attitude which appears to be that you have to make changes in order to allow for the change of divorce.
This is an arse about tit way of looking at the issue and you absolutely MUST change this perspective if you are going minimize the impact of getting rid of him and live an emotionally improved life. (There will be some downturn in lifestyle at some stage - that’s probably inevitable, but it doesn’t have to be immediate/forever or insuperable).
You are with an abuser, so tread carefully in the first instance. Speak to Women’s Aid (from work not home) and to a solicitor (initial consultations are free and I can’t believe that through work you don’t know any women who have got divorced, so find a decent recommendation). Also research solicitors specializing in DV and see if there’s any crossover with the recommendations you get. Speak to more than one solicitor so you get a second opinion. (Obviously do all this on a work computer in the office and not at home). Find out what you need to arm yourself as much as possible before pulling the plug. Do NOT leave your job/rent a new property/pull your kid from private school etc etc as a first step. Your aim is not to fit your potential future needs around what your H will find acceptable or make a minimal fuss about - anything you do he will find unacceptable and go razed earth on. Your aim is to make a life that works for your children and you, even if you have to tackle some changes to that later down the road once the dust has settled.
I don’t understand about the mortgage - it’s in his name right? Are you on the deeds to the house? There must be a way to turn the fact that the debt is entirely in his name to your advantage (If he doesn’t pay they aren’t coming after you, they come after him after all. So it’s less a case of you worrying that he will stop paying half, and more that he will freak if you’re no longer paying into it). But if what you’re saying is that it’s entirely his house on paper then you still have rights to it as a martial asset and you may well be able to stay until the children are 18 if they can’t be accommodated in a smaller place, even if you have to sell/buy him out later on. (How old are the children now?)
You need records of the DV. Specific incidents if possible. If he is physically violent - ever- call the police. Try and write a timeline of what’s happened (again leave at work). Use your voice memo app on your phone to record when he kicks off at you/children if you can do so safely. This is often surprisingly easy to do.
Do you have access to the paperwork of bills etc in the house somewhere? Take photos of what you can find. Do you know where you and the children’s passports are? Do you think you could take them into work without him realising?
The goals are:
to get control of your own income and understand the full picture of current outgoings/necessities, and the debts for which you are liable.
To get him out of house and start divorce proceedings and fight about it who gets what after that ball is rolling.
To stay in the house as long as possible (they aren’t going to repo it the first day the mortgage doesn’t get paid).
To keep your current childcare and schooling situation intact until such a time as you have literally no option but to make a change in those areas (which will be driven partly by finances, but as long as your working off joint finances that’s skewing the picture).
(Do you already claim DLA for your SEN child? Not sure what the means testing is on that but it’s worth exploring. Do you claim child benefit - might be worth doing even if you have to pay it all back annually, as it’ll give you an interim slush fund if you have it paid into your own bank account.)
You will NOT be able to do this alone - you absolutely need women’s aid input and solicitor input in the first instance. This will help you do things in an order which maximizes your chance of keeping as much of what you need as is possible, and especially of keeping the kids on an even keel while this gets worked through - because it will be hell to deal with, make no mistake about it. But it will be worth it.
On this journey you will need to fight the perception some people will have that because you earn well you can’t also be struggling financially/shouldn’t be entitled to help. You will also have to fight your own self-perception of those things. In my experience when you’re in a high income bracket/middle class then there is a massive amount of “this shouldn’t be happening to someone like me” stigma to get over. But you HAVE to do what’s best for you and the children in the long run.
In order to get help you are also going to have to admit to being vulnerable in situations where you won’t be used to it and you won’t want to do it. For instance, my guess is that the private school will find some fee help for your child to stay, certainly in the short/medium term, if you can’t pay fees as a result of taking back control of your finances. But to access that you’re going to have to go in there and admit to the abuse, admit to the whole situation, ask for confidentiality and say you want your child to stay and ASK for any help they can give. That’s not easy, but it’s worth it.
Likewise there may come a point where you need to confide in your line manager/start taking one day a week as holiday to give time to deal with matters or prevent burn out, you may need to access mental health support through work (lots of offices have well-being support available now). It won’t be easy to let people know what’s going on but you have to get into a mindset of asking for help and taking whatever you can get that’s offered. You have to face the fact that you and your children are victims of domestic violence and act accordingly. The stigma only begins to disappear when people are willing to admit what’s happening. And no-one can really help you until you do. You might be amazed to find that others you know have probably experienced elements of this themselves.
I would also ask your work if there’s a way to siphon off some of your salary to another account if you can find a way to do it without raising flags - eg. Can you pause/reduce pension contributions for a while and have them send that amount to a new account in your own name? Or to a friend/family member’s account whom you trust to hold it for you (no sending it abroad though, as the exchange rate might reduce it)?
Ending the relationship does not necessarily mean you have to prostrate yourself to some kind of minimum wage hell. You have some resources and you have to use what you have to fight your way through. Turning your life upside down and jettisoning costs pre-emptively might seem like the only way to stay safe - but you could no worse, or even better off, if you just get in the ring and duke it all out in court. And you’ll certainly have more options in the end if you don’t give up your job now.
Your relationship has made you passive and made you feel powerless. You need to get WAY more fight into you to propel you forward. There is no easy way to get through, past and over this situation, but you absolutely must fight for your children. At the moment they are growing up in an abusive home and I know that’s not what you want for them. You can’t know how all the chips will eventually fall and you can’t control your H or all the possible outcomes here. But you can take it a step at a time, show your children what’s right, and find your voice and your way through this.
If you haven’t read Why Does He Do That? by Lundy Bancroft then download a copy on kindle app or Apple Books and get reading - it’s very compassionate and insightful and certainly did me more good than years of counselling.
So instead of looking at all this as “yes, but…”, instead try to get curious about what you can and should be doing - and what might be possible if you do. My guess is you’ll need to very carefully lay a plan and execute it very fast all at once. But Wonen’s Aid and a solicitor will be able to advise. Maintain the status quo with him while you get your ducks in a row. When getting advice be clear on what you need and want - ie. I want him out of the house. I want a divorce. I want to stay in the house with the kids. I want him to help pay for the nanny etc etc.
Of course you have to do all this while maintaining the moral high ground, always acting in the children’s best interests, not letting him draw you into nastiness and so on. It’ll be the fight of your life - you just have to believe you can win it. (Sorry it’s an essay - it wasn’t much of a short cut after all).