<human>: I (30m) haven't gotten along very well with my mother since I left the house to go to college all those years ago. I can get along with anyone, I have patience in spades, but she's just selfish, inconsiderate, and mean. One of the larger points of contention is the fact that I've been agnostic for as long as i can remember, but she just interpreted this as laziness. She criticizes every decision I make, and seems to resent the fact that I'm not married yet. I still talk to her, I don't want to cut her out of my life, but her attitude just disgusts me. My sister (32) fully enables this, rebuffing any criticism directed towards my mother as everyone else's problem. 

This all came to a head recently. Last week, my sister invited me to Easter brunch, today. As I don't celebrate Easter, and I already had plans, I politely declined. This was met with a response of "Well you better cancel your plans, because this brunch is expensive and we're expecting you to pay for it." Wtf? I refused, and ended the conversation. I spoke to my sister again yesterday. She said my mother wanted to invite me to brunch herself, but she's been in tears since she found out that I said no, and can't compose herself enough to talk on the phone. My sister then demanded that I show up, and said that she couldn't believe I was acting like this since my mother was diagnosed with Cirrhosis. This is the first I heard of this, so I got more details. She was diagnosed 2 days ago, and I 'would have known that if I had bothered to ask.' I asked my sister if they knew what caused this, since my mother doesn't drink, and her response was that the doctors don't know for sure, but the stress of dealing with my 'stupid bullshit' probably played a part, and that my mother will never get better if I don't 'fix my attitude.' 

So I'm not really sure what to do here. I'm trying to stay reasonable, but the situation is growing more absurd. Thanks.

Can you provide a brief rundown of the text in within 3 sentences?
<bot>: Disrespectful mother and overdramatic sister trying to use illness to make me feel guilty, what do I do?