My narc mom is dying, with literally days to live, and my sister wants me to go see her... idk what to do

My sister called me up two weeks ago and told me that my mom is dying of stage four lung cancer, and that she was being transferred into hospice. My sister doesn't want to be alone during this, but I'm trying to respect my own boundaries. She's telling me that my mom is asking about me every day, asking if I'm coming.

I spent the vast majority of my life framing my mom as the 'better parent' because my dad was much worse (but that's another story). But I had to take the rose colored glasses off when I went NC two years ago, following an incident where she tried to get me thrown in a psych ward because I pissed her off. I wanted to retain the 'one good parent' illusion, but I couldn't anymore.

Reasons why I cut her off (tip of the iceberg):

• She allowed my homicidal pedo father to kidnap me @ 9 y.o. and didn't call the cops even tho she had sole custody, leading to years spent living under his thumb in total isolation.
• Forced me into couch surfing at my friends' houses all through high school because she couldn't handle her finances
• Never treated me like a child, more like a best friend (e.g. sneaked me into bars @ 16 y.o., got drunk w/ me while I was minor, shared very inappropriate info about her relationships with me/gave me sex advice)
• Never knew my favorite foods, colors, music, movies, etc.
• Utterly refused to accept my autism-LVL1 diagnosis, openly mocking me for 'buying into a fad' despite overwhelming evidence supporting the diagnosis
• Did incredibly nice things for me, but always with the expectation that it would buy my unconditional loyalty.

Since cutting her off, I've repaired my relationship with my sister (who was horrible to me growing up, but has done a lot of work on herself). I deperately want to remain on good terms with her because she's the only family I'm on speaking terms with. But, obviously, my mom isn't someone I want to be around.

This entire situation has me feeling extremely conflicted. I have good memories with her that make me feel like a traitor, even though I know she had ulterior motives for being nice. And I feel weak for considering breaking NC. I genuinely don't know what to do.