It's really about learning to communicate in a counter-intuitive way.  In your scenario, I'd say:

"I'm open to learning from you- show me your way to peel potatoes."

If that didn't work, I'd follow up with, "I love you and I don't want to ague over potatoes.  I'm going to step away for a few minutes and we can figure this out later."

If things stayed tense after I came back, I'd switch to, "I'm sorry if how I peel these makes you upset, that was never my intention.  Tell me how to proceed- should I keep peeling potatoes or would you rather do them?"

If that didn't resolve the conflict, I'd say, "You know what, I'm not in the mood for potatoes anyway.  I'll grab something else to eat so we both have time to calm down."  Then I'd get in my car and head for a local restaurant for one of my favorite foods.

What I wouldn't do is argue, defend, or blame- I'd stay until I start to anger, then I'd walk away.  And I would do this for everything, every single time, with very clear boundaries in place.  If you want to talk, I'm here.  If you need help, I'm here for you.  If you want to verbally attack me, I'm walking away and I'll be back when you've calmed down.

absolutely. I fully understand this now. Years ago I was so confused: she obviously knew something wasn't right which is why medications and therapy were sought. The intent to want to change just wasn't there. And from what I was told about her therapy sessions, all she was told was I was toxic and abusive (given one sided stories with zero context of course). She did admit that her rages and screaming/insults were not ok, but justified that by saying that's how she always argued, and that it was worse in childhood with endless physical altercations. It just bugged me that someone could name the issues one by one and still not change that behavior. Add in excessive amounts of thc edibles daily, and I'm not sure she even knew what was going on most times and just went into fight mode as a default.

They do not like the way you hvve peeled the poattoes. Your side of the discussion will go like this: I am sorry I did not peel them corectly...yes, I imagine I was being lazy just then. I am sorry....Yes, I suppose it was a bit stupid too, I will do better...I am sorry I did not mean to be disresctful toward you for peeling the potatoes improperly, but i know it upset you...I did it and it was wrong. I am sorry. It will not happen again." And that is how it goes. no hint of talking down to them or becoming defensive in any way, or you will regret it. The next time you need to peel the poatoes you remember and do it as carefully as you possibly can. You ask them if it is ok. They are not dys-regulated that night, so they barely glance at them on the plate. "whatever, it's fine."   

In normal arguments you can justify things, argue your point and defend yourself, but what I've learned with them is that their emotions are reality. You have to agree with their perception 100% that you're the bad guy an they're the victim or else nothing gets better.

I don't think so. In some ways it might be worse. Self employment still requires self regulating skills, executive function, and accountability. In the workplace- accountability and structure is built into the system. A person might work on a project independently but if there aren't results, coworkers and employers would notice. The employer sets the expectations.

IMHO, the aspect of BPD that impairs relationships also impairs keeping a job. Changing the type of job, or relationship, doesn't change that the person has BPD.

There can be income inequalities between spouses and some spouses don't work outside the home and still provide tasks that are beneficial to the family- child care, taking care of the house.

For some pwBPD, the aspects of BPD that make it difficult to work outside the home also impact the ability to work in the home as well.

Necessity is a motivator. We all need to have an income source in order to have our basic needs met. We all have tasks at home to keep up with. Somehow, as arranged between spouses, these tasks need to be done.

It's difficult to know if a person can manage a job or what kind of job if they aren't experiencing this necessity- that is, if someone else is providing the financial support, they may not have the motivation to work at a job.

It could be a challenge to discern the difference between support and enabling.

Treatment for mental illness is not like treatment for a broken leg.  There's not a set process to fix things (reset the bone, set a hard cast, wait 4-6 weeks, etc). 

This is an illness/injury of the mind, so the only way to actually heal is by someone mentally choosing that.  Take an alcoholic, for example, that's a psychological addiction just as much as it's a physical one.  If the alcoholic says, "I don't have a problem," then there's literally zero cure except for tying them to a bed for a few weeks.  But even then, once you release them they'll probably get drunk.

Your ex couldn't face that her conflicts came from within, so no amount of drugs or therapy can make a difference.  Like the alcoholic, she didn't see the full problem and that's the only way things can actually change.  Don't get it wrong though- the drugs didn't fail...or the therapist...or the psychiatrist or psychologist.  The process failed because the most important factor (admitting a problem and facing it) wasn't met.