Hi junglejim,
I wanted to join
ForeverDad and say Welcome
I had to live with my ex for a year from my decision to leave my marriage to when our townhouse sold (short sale during the housing bubble ) I was not married to someone with BPD (I'm here because of my SO's uBPDxw) but was married to an alcoholic so had my own issues to contend with.
I just wanted to acknowledge how hard it is to live with your stbx... .it's an incredible lesson in patience. To get some relief I tried to stay busy and out of the house when I could taking my son with me as much as I could, the library, movies, and walks became our favorite escapes. I hope you have been able to find ways to take a break from the tension too.
If you are not already doing this I would start documenting examples of your stbx's inability to cope with parenting, rages around/directed at the kids, and any suicide threats or attempts. In other words document how her behaviors are impacting your kids.
The court is not really going to care about how she treated you, it is all about what is best for your kids and how her behaviors impact them. This is what you want to focus on when you meet with your custody evaluator. Tip from my SO's experience... .even though you might feel this way and with good reason be sure to keep any anger under wraps.
How old are your kids? How are you seeing the impact of their mom's behaviors on your kids?
My SO's uBPDxw was both overindulgent and neglectful. For example at the beginning of their separation mom the primary custody of the kids. She failed to get one daughter to the dentist with a toothache for months (dad finally took the bull by the horns and got her there), and the same kid had a stomachache on a Monday and mom kept her home for a week! It sounds like she is similar to your wife in terms of her inability to provide good consistent parenting.
My SO was able to document the ways his ex was failing to parent their daughters and the court recognized who was able to do the work of everyday parenting. My SO was awarded custody M-F and 1 weekend a month, mom received 3 weekends a month. I actually think the court did a good job in our case, dad provided stability and consistent parenting his daughters needed, and mom could still see her daughters and be the weekend ":)isneyland Mom" and just do fun stuff... .no pressure... .no responsibility.
It sounds like you are doing a lot of reading (I did the same thing when I made the BPD connection between my SO's ex

) I want to share another book you might want to checkout... .
Splitting: Protecting Yourself While Divorcing Someone with Borderline or Narcissistic Personality Disorder by Bill Eddy, Randi Kreger
Panda39