Mom sick asf, but still refusing to go to the doctor + Some family trauma/vent/rant

Idk why am i posting this, kinda a rant + asking for advice ig? Idk how to deal with this situation, i am 18 btw. I am so stressed related to this

So for some context idk how long it has been since shes visited a doctor no less than 2-3 years i believe

Today she's so sick shes not even able to get up or walk properly, i have been telling her to visit a doc since so long but she didnt neither does she want to even now.

I have a relative he's a doctor she just called him took his advice. Thats what she always does she just takes his advice + if he gives any medication and thats it.

Along with that some more context as to all the stress shes carrying, her father died last to last year and her sister did too (few years older), as a result she feels obliged to take care of her sister's family, her sister's kids (she calls both of them alternatively and checks on them daily one is 27 other is 21) moreover, respectfully that sister's husband, he's such a douche. OH and she also takes care of her mother calls the helpers there daily to check whats up, calls her mother daily, btw did i mention she has 2 siblings who do none of this, one of her sibling who was the most loved ended up stealing from his father like my grandfather.. the other sibling portrays herself to be the classic victim and hence cant bear these many responsibilities

That "relative" i talked about is actually that sister's husband, why i dont trust his advices either are, firstly when my aunt was sick just before she died, apparently theres a possibility he falsely diagnosed her.... idk if its required to mention but he was also abusive w her, physically and mentally both. Also apparently he was cheating on her too and its been such a less time since she passed away hes already ready to remarry, his reasoning is if you dont want me to remarry, just come here for one month each and take care of this house, my mom literally manages his house she calls the helpers daily to help them in cooking? which i literally dont even understand just hire a cook bro but NO he says he wants someone of his own?