Sorry to hear about your divorce.
I have a relative who is going through a divorce recently, and what I understood from his lawyer was that - depending on your tenancy share type for your flat; if it is 'Joint Tenancy', it usually is a 50/50 split and if it is 'Tenancy-in-common', it will be according to share percentage both of you agreed on upon the purchase of the flat. Otherwise, it will be through negotiations of both parties on the split. Negotiations usually done through both parties' lawyers.
For my relative's case, tho his flat was on a 'Joint Tenancy', they had some negotiations and final verdict was a 70/30 split. Higher split went to the party with the children's custody.
I suggest you speak to your representing lawyer about this. Hope this helps.