I have learnt not to rely on BPDex for anything. I just wish I could leave him out of the picture altogether :'(
I know this feeling so well... .
In my case (I think this is basically for most BPDs) I went along with what she wanted custody wise although it was against my better judgement. She wanted 50/50 and it was the only 'option'. A fight would have had her go for full custody and since I was the one gone working to support the family it would have given her an advatage with the fact she was 'home' all the time. (well when she wasnt with 'him' behind my back).
Anyways, I never fought her on times or anything. Yes its a sheer hell at times but she has become so disfunctional and un predictable that even the youngest D7 told me recently, 'I wish I had a nice mommy, like Emily'. That tore me up in ways I can not describe on one side but on the other side, a kid at 7 already sees that mommy is not 'normal'. So I do not have to paint her as disfuntional and as my S10 said, 'we dont make mommy look bad, she does it herself'
My thought here is that in time they just drift out of the kids life so you having to deal with his crap will dimish over time. They fight for the kids because its a convenient weapon and they know how much we love them so they try and take it from us. The classic kid in the sand box mentality that if I cant have it, neither can you. When it looks like I dont really want it they loose interest as well. Its no longer fun
Is there no way for you to do it on your own? If you are still getting things formalized, theres still time and also as your child gets a little older, it only gets easier