I've read books, watched videos and spend a lot of time managing her with boundaries that she always plows over.
I live as far away from her as possible (on purpose) in another country but I'm going to visit her next month. The visits create so much stress and anxiety for me. Last year she raged, screamed that she wishes I would die and said her usual other choice words.
What happens when she "ploughs over" your boundary? You mentioned you walked out last time, as you should when she starts screaming she wishes you would die (or other choice words). No self-respecting person will stay and listen to that. I have walked out on my mom too. It's an awful thing to have to do. But the consequence of "walking out" is the only thing this person is likely to understand. You don't do it to punish her, but rather to protect yourself. What other boundaries does she "plough over"?
It sounds like you are "staying with her" for the whole two weeks. Have I got that right?
How about staying there for say 5 days/nights, and then planning to go stay with an old friend or family for a visit for a few days to get a breather. Or schedule a long weekend for yourself somewhere else. Then plan to come back again before you fly back to your home country. Might breaking it up like that help?
Two weeks is an eternity with a high conflict person.