84 year old NMom has cancer

I’m 56 yrs old. I’ve spent most of my life people pleasing and trying to be good enough. About 3 yrs ago, my husband said “oh my god-your mom is a narcissist”. I shared this with my therapist & his reaction was basically a kinder version of “well, duh.”She’s 84 years old and has cancer. I work full time and have a family, but I still find myself being manipulated into taking her to all of her appointments. I’m exhausted. There are moments of appreciation followed by her complaining and criticizing. She won’t do the things basic she needs to do to feel better (drink enough water & eat). It’s the drs job to heal her. She tells everyone how wonderful I am but is passive aggressive to me. I’m constantly feeling guilty for not doing more, but i feel like she’s stolen enough of my life. I could go on and on but I think ya’ll get it. I’ve been gaslit so much I always think I’m the problem. I don’t know how to be true to myself and be kind and set boundaries.