Back in March my mom (50s) and sister (22) stopped got into a fight and my sister is saying she will never forgive mom and she has tried to turn me (23) against mom too.

To give some context. Six years ago our parents marriage ended when mom found out dad had an affair and father a child with someone else.

Dad ended up becoming official with the other woman and moved in with her and their child. I severed ties with dad at the time. He’d never been a very engaged dad and though he said he wanted to be more engaged now that he had a new baby, that made it worse in my eyes.

That he’d only step up after he had a baby 16 years younger than me? Nope. Not happening. My sister didn’t go to see him for more than a year too but then after talking to mom she decided she wanted to try with dad. Mom told her she would never stop her from doing that if she wanted a relationship. My sister told me the real draw was having a younger sibling. She tried to convince me to have a relationship with dad for the same reason but I told her I didn’t want to know the baby, who was over a year old by the time she tried to convince me.

That created a weirdness in our relationship because she wanted us ALL to be a family. But I told her I would never be a part of that family. I told her in my eyes I never had a dad, just a mom. And there is more than a little truth in that. He was never there for us as kids and I don’t want to give him a chance to make it up to me.

My mom asked my sister to respect the fact she could never forgive dad and would never want a relationship with dad or his family. She told her she would be civil for her sake and would be polite at her birthdays, graduations, weddings, etc but that was the most she would be willing to deal with him. Which my sister said was okay.

Then back in March my sister texted mom and told her she was dropping off dad’s 6 year old and 4 year old to her house so please answer the door ASAP because dad’s wife was rushed to hospital and she wanted to be there for dad and they needed a sitter. Mom texted her back no but my sister carried on to the house anyway and mom simply didn’t answer the door. My sister tried for like twenty minutes before she left with the kids. They ended up going to the hospital with her but apparently they were asked to leave unless the kids were patients. They were limiting the kids access to the hospital.

My sister ended up confronting mom a few days later, which is when the fight happened, and she won’t talk to mom now. My sister has told me all about it repeatedly, shown me the texts repeatedly, and called mom names repeatedly to my face. Last week she finally asked me how I could still talk to mom after that and she told me I needed to be on her side. I looked my sister straight in the eye and told her that I would have kept the door closed on her too. I told her I never would have agreed to babysit those kids. So I wasn’t on her side.

My sister told me I’d have been cruel beyond words to not answer the door when I knew someone needed to take care of the kids. That mom was cruel beyond words. I told her those kids are not mine or mom’s problem and she accepted them, she loves them, she has a relationship with them but we do not.

My sister’s still talking to me but only to give me shit about what I said. She can’t wrap her head around the fact I wouldn’t support her and would do the same thing mom did. AITA?