All the focus in your post is on your duties, not on hers.
I obviously don't know your relationship from the inside, but I experienced similar and it was relief to get away from it.
I think a major complication is that she's somewhat manic in that she has highs and lows. Her lows are extremely low. When she's higher though, she can be very pleasant, kind, good to her family, etc.
I find it very difficult to nail down who she is on that spectrum, or where she might eventually land between those states, and how I can judge her or my decisions based on how things fluctuate so much.
The word gaslighting is absolutely accurate, though. She does this a lot and I wish she didn't. I'm vulnerable to it because I tend to blame myself and hesitate to engage in confrontation when I'm uncertain of myself.
If you don't have kids, you should leave her. People's characters don't usually change or improve.
There's an interesting set of perspectives around this type of problem in psychology. Whether you look at popular moderns like Alain de Botton, Jordan Peterson, ancient philosophers, religion, etc. there is a recurring theme that commitment to a person matters, and without it, things kind of fall apart.
I find this interesting and compelling. I don't expect life to be easy, and I think welcoming and anticipating challenges is very healthy. This sort of problem does straddle boundaries that I find difficult to define, though. At which point is enough enough? When do we decide the commitment is no longer warranted? How "easy" should a relationship be? If I leave, will I be foolish for seeking anything different?
Not to drag this on - I find the topic very fascinating for both personal and more general reasons. This is a problem I believe a lot of us face. If I can't sove it for myself, I'd be happy to understand it better if only to serve my friends or children eventually.
> People's characters don't usually change or improve.
I wish you were wrong, but this does seem to generally be true. There are exceptions of course, but it seems inadvisable to ever hope for it to happen. It takes incredible work, and it's work that a lot of people don't have the knowledge or tools to understand or work with. Personal growth is perhaps one of the greater challenges in life.
Anyway, thanks for the discourse. I appreciate the advice. I should make apoint to look out for myself more when I sense gaslighting is occurring.