We have a wonderful little 6 year old that is such a trooper... the struggle now becomes how do we effectively co-parent and figure out shared custody in this situation.
Layer on top of that the financial threats she keeps leveling at me...
When addressing the BPD perceptions and behaviors, you will find that it is seldom "we" figuring out parenting. People with BPD (pwBPD) typically are more likely to obstruct and sabotage than cooperate. To the extent possible you need to do your best to have sufficient authority, usually assigned by the Real Authority, domestic court.
For example, shared or joint custody is a nice concept... for reasonably normal parents. But a pwBPD will often view that as "I will make the rules and you will acquiesce." More or less.
Often the sense of entitlement/control exhibited early in a separation causes mediation to fail. Judicial intervention and time will eventually make a settlement possible later in the divorce. Most of us did reach settlements but usually not early in our cases. In my two year divorce case, I arrived at court on Trial Day and was greeted with the news she was ready to settle, she couldn't postpone reality any longer.
Division of financial assets and debts is fairly straightforward, a lot is covered by standard formulas. It's the custody and parenting schedules that are prone to getting stuck. Your spouse can demand whatever, but if you don't think it is appropriate then you as parent have a right to stand up for yourself.