The house, all money in the accounts and investments/pensions are marital assets. As you are married you'll be get a share. It doesn't matter whether you're on the mortgage or deeds, the house is a marital asset. The only thing that's excluded are inheritances (and only if they have never been put into a joint account).
Unless he's been very clever financially (and paid an accountant to put things in trusts / made them business assets), you should be fine.
Get a decent divorce solicitor and they (and the judge) will make sure the split is fair. This doesn't necessarily mean a 50/50 split, but a split that ensures both parties end up with equal living standards post divorce.
As well as the divorce itself, a financial order (clean break) is required to sever all financial ties between you (without that, you still have a claim on each other financially even if no longer legally married).
If a judge deems the financial order to be unequal they will refuse it and force the parties to go back and re-do it (ie one person being screwed over - likely due to financial coercion by the other).
It sounds like he's a a*hole and desperately hoping you'll roll over and not fight for what you're entitled to. If he's reluctant to produce financial information the court can force him to do that. Hopefully he'll be forthcoming - it's very difficult to hide assets/wealth away where they can't be traced without a very good (and expensive) accountant. He might think he has done a good job himself but any forensic accountant will easily track it down. If it gets to that stage and the court is forced to dig deeper themselves, the judge again will take a very dim view of this and make sure that the costs associated with it comes from him share of the pot.
To put your mind at ease now book an initial consultation with a divorce lawyer - most will do a 1hr chat for free before you appointment them. You're not obliged to go with them for the full divorce.
If costs will be an issue, if you are on a low income you can get help with the legal costs of the actually divorce process itself (the cost of filing the papers with the court), but the legal fees for advice and solicitor costs are usually deferred until you receive your share.
Also - check out The Legal Queen on insta/FB. She is a divorce lawyer and does lots of videos giving free advice (I also think her firm does the 1hr free consultation thing). She does regular follower Q&As as well.