>>would the starting point be 50:50 for both,<<
Yes.
>>What can I expect as best and worst case? <<
Worst is that your wife may be able to show that her property remained hers, that there was no mingling, so that it therefore did not become a marital asset and ought to be excluded from the 50/50 split.
Best is that her property gets included in the 50/50 split.
Of course, you do not say whether there are any dependent children and what your respective earnings are. Either or both could significantly affect the outcome.
