@Plantbasedpeanuts
From the 'financial security' point of view, I can see why they've done this. It protects your children from having their inheritance taken away from them by your DH. I assume that the money is going to be in some sort of trust until they reach a certain age. And I assume they wouldn't change this if you left your DH.
The thing is now that they've cut you out, in actuality they have freed you to leave him. You've 'lost' all you can lose (their money) so what do you have left to lose? Nothing, unless you think they'd give the children's inheritances to the Dog's Home or something. And since you and DH are married and he is wealthy, as his wife you'd be entitled to a share of that wealth, assuming that it is in his name and not in some sort of family trust.
I think it would be a good idea for you to speak to a good solicitor. Tell them as much as you know about your DH's 'wealth'; where it comes from, how it's titled, etc. Let them advise you as to whether or not you'd be entitled to anything. Certainly you'd be entitled to child maintenance, possibly he'd have to buy you out of the marital home. Depending on what the solicitor advises, you may find that you are able to leave. Perhaps your standard of living wouldn't be as high as it (seemingly) is now, but would that really matter if you were happier without him around?
As far as your parents, my parents were very religious, too. But when I told them I was divorcing and the reasons why, they took my side and supported me. I don't know what the religion is (and I am not asking) but do you think you'd be able to speak to a priest/pastor/imam about your marriage? Perhaps they would agree with you that you'd be better apart.