Kathy, ...your response is one I have heard many times and very typical of someone on the outside looking in.
Joe, clearly you, Kathy, and Tige all agree that you should do whatever is in the best interests of your children. At issue, then, is what is best for them. None of us on this forum can know, with any certainty, what that is because we are all "on the outside looking in." We have never met your family. We don't know how strong your W's BPD traits are. We don't know how old the kids are. We don't know how abusive she is to your children when you are present -- versus how abusive she is when you are absent. Hence, you are the only person who can decide whether they are better off with you staying or leaving.
As a GENERAL proposition, Kathy and I believe children usually are better off when the fighting parents separate into separate households. One reason is that toxicity in the home usually goes down when the abused spouse leaves because that spouse -- despite his continual efforts to sooth the BPDer -- does more damage than good. His soothing efforts are counterproductive because he serves as a frequent TRIGGER to the BPDer's fears of abandonment and engulfment. In contrast, children are so fully dependent on the BPDer that, with HF BPDers, they typically do not strongly trigger those fears until puberty.
A second reason is that the vast majority of BPDer parents are high functioning (HF). If your W were low functioning, you likely would never dated her, much less married her. I mention this because, although a HF BPDer can still satisfy 100% of the diagnostic criteria for having full blown BPD, her ability to properly raise children far exceeds that of a LF BPDer.
A third reason is that, by staying in the marriage, an abused spouse puts himself at constant risk of being arrested on a bogus charge and thrown into jail, as happened to me after 15 years. This often happens when the BPDer W decides she wants more "validation" that she is "The Victim" -- or, when she is fearing abandonment, decides she wants the added leverage (of having you declared a physical abuser) for any future custody battle that may occur. If that occurs, the abused spouse may end up being able to protect his kids only a few hours a week, during supervised visitation -- far less than the 50% he could get by leaving early, and far less than the 100% custody he might get if he builds a careful record using a VAR to capture rages and the kids' screams.
For these reasons, I agree with Kathy that -- as a general rule -- the kids usually are better off when the parents split up and the constant fighting stops. Whether this "general rule" applies to you is a judgement that only you can make (hopefully, with guidance from a professional). Certainly, it doesn't apply if -- as you seem to suggest -- your W is badly abusing the kids in your absence and you have no evidence to use against her in court.
We've been to 4 different marriage counselors and they have not been much help (MC doesn't usually help with BPD. Generally they don't know how).
I agree. I took my exW to several MCs and it was a total waste of time and money. And, if the BPDer is unwilling to work hard in therapy, a team of psychologists will be equally useless. I spent a small fortune taking my exW to weekly sessions with six different psychologists for 15 years -- all to no avail.
I'd love to find a MC that is also a psychologist.
It is highly unlikely it would make a difference. It is rare for a BPDer to have the self awareness and ego strength necessary to be willing to fix herself. Therapist Shari Schreiber says you have a better chance flying to the moon strapped to a banana than ever seeing a BPDer stay in therapy long enough to make a difference. And, even if you persuade her to stay in therapy -- as I did with my exW for 15 years -- the chances are good that she will only play mind games with the therapist, at enormous expense to you.
I am looking for people in my situation who have found ways to make things better for themselves and their families. ...Tactics that have helped others deal with the outbursts, the rage, anger, jealously, etc.
Joe, the best place for that information, IMO, is the "Raising a Child when One Parent Has BPD" forum at BPDfamily.com. There you will find a hundred other people who've been there, done that.
My experience is that, if your W has strong BPD traits as you believe, there is not much you can do other than leave or continue tolerating the abuse while walking on eggshells to help reduce it a bit. That way, your kids will have the benefit of less screaming -- largely offset, however, by the harm of seeing their own father being a doormat.
As you already know, enforcing your personal boundaries is essentially the same thing as choosing to leave because, if your W has strong BPD traits, she almost certainly will not tolerate that. She will tolerate your presence in the home only as long as you continue validating her false self image of being "The Victim" by allowing her to abuse you and blame you for every misfortune. Once you stop doing that and stand up to her, you will be of little use to her.
One possible remedy, then, is to start standing up to her more -- in a very calm way and with a VAR running in your pocket. Of course, you will get a dramatic increase in tirades and temper tantrums. But you may collect enough recorded evidence that, in your lawyer's opinion, would win you full or primary custody of the children.
Yet, as difficult as it is in our court system for a H to obtain 100% custody, the kids may be better off if you continue on your current course of being the frequent doormat. Indeed, if your W's BPD traits are not very strong, you may find that you don't have to be a doormat at all because she will be able to tolerate your enforcement of boundaries. That is a judgment call that only you can make.