Thank you for your question
My name is Clare
I shall do my best to help you but I need some further information first
How old are the chidlren?
How much is the house worth and how much is outstanding on the mortgage?
What other assets are there and what income do you each have?
How much would a cheaper three bedroom property in the same general area cost to buy?
In that case in the event that the worst happens you will be able to call for a sale of the property.
Your wife will receive sufficient monies to allow her to purchase a home for her and the children - and you will receive the balance which you can put down as a deposit.
You will however have to wait for any further capital until your youngest is 18 or your ex cohabits.
I hope that this is of assistance - please ask if you need further details