A significant amount then ..... Way beyond what could be considered money to buy essentials that would allow that person to 'move on' with their life pending a property settlement (which is considered a legitimate reason in family law)
So a few options ...
1) Ask for at least 50% to be transferred to an account in your name ..... If sh/e refuses to discuss it or refuses, invite them to mediation ( you will need to attempt mediation anyway before fling for property orders)
2) If mediation fails, you file an initiating application with the family court for property settlement, along with an interim order for $xxxxx amount or an application for spousal maintenance pending a final order ..... if you are going to do this DO IT ASAP .... If that money gets spent, you are going to have a VERY hard time trying to find out what it was spent on & if it is grounds for an add back under family law ..... DON'T DELAY
If /when a settlement is filed, the court can go back over 12 months or more preceding separation to look at finaces, so make sure you have as much proof as possible of your finances from at least 12 months prior to separation to settlement time
3) IF the removal of that money means you are now unable to pay for essentials then you can seek a family violence order on the grounds of financial abuse (taking control of finances, stopping access to joint account etc) ..... That will have the effect of bringing that person before a magistrates court fairly quickly .... There you could negotiate to have some money restored to you