. . . recently every other day he is fighting and says I ruined his life, am a monster, toxic, cold, etc.
Hi there Trony,
You've come to the right place. The situation must be really hard on you, simultaneously trying to manage your husband's BPD outbursts, taking care of the kids, and on top of that, probably over-functioning for your husband on many fronts (housework, finances, scheduling, paying bills, etc.). That can lead to burn-out and resentment, too.
Though your husband is prone blame you for his woes--calling you a monster and toxic--my guess is that there might be other things going on his life making him feel bad, maybe inferior, unloved or unimportant. A possiblity is that he's jealous of the attention the kids are getting. What does he do? He basically acts like another kid, in a vain attempt to get your attention. But it doesn't work well, because he's not a kid, and deep down he feels ashamed.
I'm not sure from your post if your husband is working, but maybe he feels emasculated by you, because he knows he's not pulling his weight on the home front, possibly financially. So rather than appreciate everything you do, he might try to trivialize your contributions while claiming that he does "everything." Does that ring any bells? It could be that he's plagued by insecurity, and he might be trying to put you down, in your proper place, because you're upstaging him all the time. Thus he'll call you a "monster," "toxic," or maybe stupid/narcissistic/lying/ugly/lazy. Typically those are projections of things he thinks about himself. Maybe he's threatening divorce because he knows he's letting you down, and he wants to beat you to the punch? Or maybe a divorce threat is an attempt to blame YOU for causing all the trouble in his life.
If you want to know what's bugging your man, I'd advise to listen for the feelings behind his outbursts, not so much the facts (which can be highly distorted). As an example, the pwBPD in my life was preoccupied with feelings of inferiority and living like a child. She ruminated about these feelings so often that they tended to bubble up as projections and accusations: "You're condescending / You're controlling / You treat me like a baby / You can't tell me what to do / I'm an adult, I can do whatever I want!" That was really code for, "I feel inferior, I'm lagging behind my peers, and I'm mortally ashamed about that. I can't do what I want in my life because I feel powerless. I'm stuck like a kid."
I think you're doing well to enforce your boundaries and not get drawn into his meltdowns, which would only feed the fire of his ire so to speak. Sure, he'll try to egg you on, by being nasty, berating you and threatening you. He doesn't fight fair, so you're better off not engaging in my opinion. Only engage when he's calm. In the meantime, you can think it like giving him an "adult time out," not dissimilar to how you'd deal with a kid having a meltdown. When having a meltdown, a kid (and an adult with BPD) is overcome by emotions and can't process words or logical arguments anyway. In short, they are NOT listening to you, so it's better to stay silent in my opinion. You give him more time and space to self-regulate, a skill that he hasn't learned yet. But if your husband is a threat to himself or others, you need to call 911 in my opinion. You have yourself and your kids to protect.