If you are prepared to make an ultimatum and follow through with it (file for divorce, lock up finances, etc) then by all means do so... but not just because they refuse.
I would wait until they actually violate the ultimatum. If you for example tell your spouse to stop using the children's college fund to support a gambling habit.. and that you will lock finances up if they do so again..
Once they make that withdrawal then you follow thorugh...
It's all on pp 230 - 31 of the text...
This all consistent with other self-help programs (al-anon, codependence....) plus the other DB techniques. Act as if, 180s, detach, GAL etc. DB is unique just like all the other programs. Can't imagine any mental health professional not advocating healthy boundaries.
M22,H45,W45 S21/18D12 Retain faith that you will prevail in the end, regardless of the difficulties and at the same time confront the most brutal facts of your current reality, whatever they might be.