You have begun to think about separating from your spouse, but you are concerned about the financial consequences. Below are some tips to protect yourself while not getting on the wrong side of divorce law in Canada.
If you are concerned that a spouse may empty a joint account, then you should consider closing all joint accounts. Should you decide to close a joint account, you can split the funds with your spouse or keep the funds in a separate account until the matrimonial property has been separated. What you should avoid doing is spending any of the funds before they have been divided. Any amount you spend from a joint account will be accounted as interim division of property
Unfortunately, mortgages cannot be closed simply, and so a discussion on who and how you and your spouse will pay your mortgage will have to be had. For credit cards, you should pay off the debt and closeout joint accounts. If the balances are too large, the credit card balance should be transferred or the card stopped and a payment plan developed with the bank.
Any locked in joint savings should not be withdrawn. Taking out an RRSP will result in tax penalties of course, and it considered an interim spending of matrimonial property and can negatively weighed against you. Instead you should keep an eye on all joint savings and leave them alone until division of matrimonial property is completed.
As you can see, your immediate joint accounts should be closed, while savings and mortgages should be left alone until a division can be completed. Though you may believe an account is in your name alone, it can be classified as matrimonial property and spending it could be perceived negatively by the court.