I am divorcing a partner with BPD... . We have two children and she will not negotiate anything regarding custody. She feels because she was the primary care giver she should not share custody.
This is typical Entitlement and Blaming. If she looks bad then she will try to make you look worse than her, generally though allegations and alienation. Your stbEx feels Entitled and therefore you get nothing. Well, guess what,
family court, though often seen as biased, glacially slow and stuck in old policies and procedures,
does have one thing she doesn't have... .Real Authority. Family or Domestic court's Authority trumps hers. Yes, they will likely treat her far better than she deserves, but at least you will get better treatment from court than from her.
For that reason, seek help from court. Keep the case moving. Get the best temp order you can get from the very start because it is really hard to get changes made later. It's almost like the court feels that if it's 'working' in a temp order then why change what works? You can't reason with her so don't bother trying. She's likely to see your reasonableness as weakness.
Court may order mediation. Good, do try - so you can report to court that you tried - but realize her demands will be unrealistic and even the mediator won't sway her. The fact is that mediation almost always fails unless it is just before a major hearing or trial near the end of the case when you may hear something halfway decent "on the court house steps" just beforehand.