were doing EVERYTHING OURSELVES because u went and got this job which has us doing everything not to mention how many appts you keep canceling
Oh Geez. She has it in her head that you're responsible for her and these kids, and that anything that she might do is voluntary, and she deserves a prize and a parade. She is a fool, truly.
And the boyfriend!
The reality is that her job (and the man's if he has decided to step into a role of responsibility, and he has) is to "do everything." You are peripheral.
As I see it there is no way that communication with her will lead to any positive outcome, cooperation, or shared understanding. Her assumptions are totally flawed, based upon either her capacity, and/or mindset about life, and your past pattern of choices to help her, which you are changing, as we speak.
The best thing to do is what you're doing: keep child protective services advised, step back and let her find resources, and step up herself; and cut off communication until she can demonstrate respect, or a facsimile of same (I am quite skeptical of her willingness or ability to see the reality of the situation she faces, which seems a prerequisite to her understanding just how much she owes you, and just how much she has been protected by you, and just how much she has to lose without your involvement.
What she cannot see is that your help (when, how, how much, what kind) is determined by you, not her. It is not your responsibility to help her see this. She will only abuse you more if you try. If you choose, you can advise her by text when and how you can help her, at some point. But I believe that should be contingent upon her treating you respectfully, and keeping the guy totally out of the equation. But I do not see her coming to this position, without a great deal of suffering on her part, to teach her.
It is totally nuts that this man feels the right to insult and berate, let alone threaten you.
I will say that I believe as long as he's in the equation I would step way, way back. I would see the children, if that's possible, but only if it does not involve interaction with him, and very limited interaction with her.
This is a toxic, abusive and potentially dangerous situation. It has far exceeded the problem of limit-setting and enabling. It's become potentially dangerous, in my view. And it may soon enter a stage where there are legal ramifications, for her, for him, and for the children. I would stay as far out of it as I could. Really.
Bottom line: these people are out of control. Their thinking is disordered. This could well explode. None of this is your fault. Be very, very self-protective.