Hello TiredPsychology and a warm

Join the club with others who are navigating the complexities of BPD relationships. It's interesting that usually the impact of BPD is felt far beyond just the core relationship. It can impact not only romantic partners, but also parents, siblings, children, friends, and extended family. You're in good company with members here who are coping with similar situations.
The first thing that strikes me about your post is that I'd like to learn more about the level of closeness you have with your parents. Each family is different -- there is a wide range of family norms, cultural norms, and social norms for closeness/sharing. To you, does the level of sharing you have with your parents feel pretty normal, too much, not enough... other...?
I'm also curious about this:
she then started taking a medication which changed her behavior, making her pick fights every single day.
What the medication is for, if you don't mind my asking? BPD plus other health (physical or mental) issues can be a big challenge.
The issue I have is that she has BPD.
Does she have a diagnosis? If so, does she accept it? Is she doing any treatment/therapy?
If no diagnosis, did she say something like "wow, I wonder if I have BPD", or did you put some pieces together, or?
She literally will never consider that her feelings (while valid) aren't always going to be reliable, and that her feelings about my parents don't trump the actual need to make a living. We've been fighting about this for weeks, often staying up until 3 am just trying to resolve this but it isn't working. She refuses to see anything but "narcissistic parents" and "bad family dynamics." How can I show her that this is literally just employment? How can I stop the near constant fights and drama? I'm getting so burnt out. Every time we discuss anything related to the issue she gets sarcastic and passive aggressive, and it's really frustrating.
This sounds like part of the core of the issue.
If BPD is in fact involved, it's important to remember that it's a serious and impairing mental illness. We wouldn't try to have 3am arguments with the man on the streetcorner who is arguing with the sky... but because BPD sufferers can sometimes present as "normal" and "in touch with reality", we get sucked into trying to reason with them, argue them into our position, "get them to see reality", etc.
When BPD is in play, "generally normal" approaches to conflict will likely not be effective and can often be deeply hurtful and counterproductive. For your relationship to have a chance, learning new (and often unintuitive) tools and skills will be critical. Before things can get better, we have to clean up our side of the street and stop making things worse.
A great place to start is our overview of
The Do's and Don'ts in a BPD Relationship. Take a look when you have a minute -- anything there resonate with you?
Looking forward to learning more about your story;
kells76