The best way forward is an immediate Divorce petition as that give you the widest spectrum of financial options
I have little doubt that within any final settlement you will receive all of the equity in the house as it is the only asset that the Court has immediate control over
You can certainly apply for Maintenance Pending Suit - and also Child Maintenance - you cannot use the CMS as he works abroad
The principal problems with be obtaining disclosure from him and enforcing the maintenance Orders
However to an extent I suggest that the fact that he will be defiant to the court will assist you with regard to the settlement and the court will simply assume he has more assets that you think and award you the house outright because of his intransigence.
Enforcing the maintenance Orders can be dealt with via his Hong Kong accounts- if he does not close them - and ultimately by the threat aOrders through the use of the threat of imprisonment when he comes to the UK
I appreciate that this is not an ideal solution but given the fact that his assets are abroad sadly there is no way around it.
The starting point is the divorce - and you have ample grounds to divorce him based on his Unreasonable Behaviour.
You can start the process using the details here
Please ask if you need further details