As someone in throes of an acrimonious divorce, I can perhaps tell you about what I think that really means.
Firstly, whatever threats he makes are empty, foundationless and because he too has likely never been divorced, totally within his belief that he is the master of the universe and that divorce law is biased again women, and that he has more 'rights' because he has the money. It's not - it's biased against twats.
I would urge you to seek legal advice now - to dispel all the common beliefs you have about his entitlements, and yours, you'll be rather relieved I suspect. I know I was - it's just enforcing my rights that is rather painful and comes with a barrage of problems, largely of his making.
If you maintain your shit marriage, then it gives him a long time to prepare for leaving, and ultimately all you are doing is postponing the ending of it until he decides he wants out. That means he may do stupid things with the family finances. You may then be left out of the blue, and really in a mess to resolve. The first person to take control has the initial advantage.
That does not mean they affect the outcome of the divorce settlement or childcare arrangements in any way. The law does not work like that. So his 'why should you get the house I paid the mortgage' does not come into it. The question is: can you and the children afford to stay in the family home taking into consideration your earning capacity, his earning capacity, pensions, saleable assets etc etc. This is unique to your marriage - so any beliefs you have about staying in the marital home are misguided until you get sensible, independent legal advice. Chances are you will stay in the marital home, possibly with a Mesher order (delaying a sale until the children come of age), possibly owned outright by you, possible sold and you move, possibly with him keeping it, and you moving to a new house. The possibilities are endless - it all comes down to what can be afforded and the children's needs being served. This will take time to resolve.
The law also does not recognise any twattishness within the marriage. It matters not one jot who had an affair, who had the smelliest farts, or who was the most unreasonable. It is only concerned with the arrangements for the children, the arrangements for the children, the arrangements for the children and the finances. It that order! He will not 'get' 50% access because he decides that. It's a lot more complicated than that!
It is largely a pragmatic process. You rant and rave and cry with your friends about the divorce - but I promise you it does end, you won't feel dreadful forever. What I've found in myself, was that whilst I was utterly devastated for three months, now I'm four months down the line, I just hate him. I want him to go away, I do not want him back. I miss him - but not this twat I'm married to now. The initial awfulness of the emotion goes away as you learn you need to protect your/your children's future. I still have some very sad days but I am accepting that the marriage was now flawed and it in MY interests to move on. He can go to hell for all I care.
Separating now, and him remaining in the family home (his choice - fine, but your service as cook, maid and PA are also dispensed with).
It will be unpleasant - and it will be a sustained period of awfulness rather than the slow drip-feeding of awfulness that remaining will mean.
Much of my beliefs about divorce have been proved false, misunderstood and born about because of what you read in the media, and fear! Living through a divorce is an emotionally intense time, however, as much as it only takes one person to make it acrimonious, the other person is just 'unreasonable'. I suspect it is better to be the unreasonable one (ahem!).
I suppose what I'm learning, and trying to my damndest to apply personally is that divorce is largely a legal process and can be very straightforward, and done very cheaply. Sadly, I have no hope of that now unless I forego a lot more money than the divorce costs (again, a choice as long as I can stand it, I will learn to tolerate this). It doesn't have to be this way, but it is wholly depending on the other person being co-operative.
The difficulty in divorce is that it is largely two issues competing with each other: the pragmatic ending of the marriage through a legal process and the emotional rollercoaster of hurt, anguish, stress and anxiety. The very conditions that sensible decisions are least capable of being made in!
Divorce involves a great deal of decision making, of putting your feelings to one side, and not reacting emotionally but pragmatically. You do not get 'compensation, retribution or resolution' through divorce - it does not feel like a 'fair' process at all because you've been treated appallingly.
It can be a thoroughly unpleasant experience - but that said it does end. Shit marriages never do until the other person does the 'decent' thing and expires.
So don't entertain any threats of what he will do with the house and children. If he chooses to be a twat in the divorce - so be it. You merely behave unreasonably - e.g. not doing as he says but because that is not in the best interest of you or the children. Not because you wish to make him suffer or get revenge.
That's my take on it.