There’s a lot of assumption about your circumstances OP, and a lack of regard for the fact that you appear to be substantially disabled, which, as you so rightly say, limits your options as to how much you can do at any one time.
I’ve been confined to a wheelchair since birth so I’m speaking from the perspective of someone who understands disability, and having read the whole thread I’ve had a good think. For what it’s worth I think the people jumping to conclusions that your DH is abusive, is typical of MN, as is the urging to leave him from some posters. And I agree, it’s fairly insulting that the assumption is you would move out and rent somewhere while your DH keeps the house - especially when you read thread after thread on MN urging others to make sure they take legal advice and get what they’re entitled to. Why should your disability mean you wouldn’t be entitled to do the same ? And yes, the fact that you have children seems to have been overlooked - if you have custody, why should you be the one to leave, and why, in the detailed financial examination by some posters, has his contribution towards his children not been considered, or mentioned ?
You don’t say how long ago you became disabled, except that it was since your marriage. If it’s fairly recently, could it be that your DH is having difficulty coming to terms with the changes disability brings ? There’s been a lot of criticism of him, from myself included, because the knee jerk reaction is that it should be obvious that your needs come first, and that he’s being very selfish in not considering you more. There’s also the possibility that he sees you as he always has, so the needs you have now haven’t registered fully, because he sees you, and not the disability, and is carrying on ‘as normal’ so to speak.
But he needs to understand and accept that you now have extra needs that need to be financed from time to time, and that this is what PIP is for. You may not always be in the same financial position as you are now, and you made the point in a subsequent post, that your PIP award is only for a couple of years, and may change at the next assessment. With that in mind, I think you have the right idea in thinking that it should be separate from the ‘pot’ and left to build up to cope with your future needs, should you require them.
Being newly disabled is traumatic. It brings about major change, affecting you both. So I think you need to sit down together and be honest with each other about all of these issues, and how you see your future together. It may be difficult but it’s the starting point to sort all of this out. I hope you can find a way forward.