I think it is a grey area where what we call MLC shades into something which is a really unbalanced pattern of behaviour. Most MLCers here do and say some pretty awful things, and some of it goes on for a long time.
My xh was generally unremittingly hostile to me for the best part of 5 years, with occasional forays into normal. They can stay angry for a long time.
What I think we have to do is back off from the weirdness, and not feed it. This is one of the many reasons why we need to detach.
There are 'mild' MLC and more severe ones, it would appear from the variety of experience reported here. Some spouses are able to go on talking to each other throughout, which I used to find astonishing!!
Tad, if your xw is really unbalanced she will need to get help at some point. If it is extreme MLC, and thus mainly directed at you and her immediate family, or part of it, it may eventually blow itself out. I have no claims to be a professional therapist, merely an observer, but it seems to me that you are inadvertently feeding her anger.
if you could stop all contact, and take no notice it may blow itself out more quickly, or turn on someone else who may be in a position to advise her to get help.
You could, by your availability, be making the situation even worse. We want to be there for someone we love who is sick, but MLCers often tend to see us as the problem.
You come across as a co-dependent couple pre MLC, whether or not you realised this. Your xw may be trying to break free from this, in an immature and destructive way. It can be helpful to see the MLCer as fighting for their life, when they feel they are drowning by staying in their old life. We can only respect that decision and give them the space they need.
Also we have the right to our boundaries, and to be treated with respect.
While divorce is arguably 'only a piece of paper', at the same time it dissolves any legal rights your wife has to say and do what she pleases to you. In many places there are actually laws in place to protect former spouses from on-going harassment . . . . I do not say this to encourage you to be litigious, but to remind you that you do not have to tolerate her behaviour. Legally she is nothing to you, and has no rights, apart from what the divorce settlement gave her, and I doubt it was the right to be abusive.