No one can determine a fair settlement without knowing the size of the pot to be shared and the parties' respective incomes.
At this stage disclosure is entirely voluntary but it's difficult to agree a settlement and for a solicitor to advise when one party doesn't know the value of the assets held in sole names as well as those held jointly. The result is often protracted negotiations, expensive legal fees and damaged long term family relationships if there are any children.
If you refuse the other side could instigate court proceeding and then the court would require a schedule of assets and liabilities.
We've always kept our assets separate, other than some stuff like the house, shares and some savings. We split the joint cash already but I've been saving extra from my salary whilst she's been spending all of hers and even used some of her share of the joint cash.
Also, she refused to start a pension but I've paying into mine for years and she gets half the value of that, despite only being married for a few years with no kids.
Plus, she won't even try marriage counselling or anything, doesn't seem right at all.