AITA for telling my sister I would have kept the door closed on her too when she looked for me to side with her against mom?

In a quiet suburb, a family’s old wounds tore open when a sister demanded her mother babysit her father’s children from an affair. Picture a tense doorstep scene: a young woman with two kids, knocking in vain as her mother stays silent inside. The sting of betrayal from years past hung heavy, fueling a fight that’s now split siblings.

The original poster (OP) found themselves caught in their sister’s crusade to rally against their mom, but their blunt loyalty to her sparked a fiery clash. This isn’t just about babysitting—it’s about boundaries, betrayal, and where family ties fray. Readers can’t help but wonder: was the OP’s stance fair, or did it pour salt on an already raw wound? Let’s dive into this tangled family drama.

‘AITA for telling my sister I would have kept the door closed on her too when she looked for me to side with her against mom?’

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.

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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.

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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.

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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.

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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 s**t 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?

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This family feud is a messy knot of hurt and boundaries, with the OP’s sister pushing a burden no one signed up for. The OP’s support for their mom’s refusal to babysit reflects a deep loyalty rooted in their father’s infidelity, while the sister’s insistence ignores the emotional weight of that betrayal.

The sister’s attempt to drop off the kids without consent was a bold overstep. The OP’s mom set clear boundaries years ago, agreeing only to civility, not caregiving. According to Psychology Today, 60% of people struggle to forgive infidelity, and for many, like the OP’s mom, reminders like affair children can reopen wounds. The sister’s expectation that her mom should step up dismisses this trauma.

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Dr. Janis Spring, a family therapist, notes, “Boundaries after infidelity are crucial for healing” . Here, the mom’s closed door was her line in the sand, and the OP’s agreement aligns with respecting her pain. The sister’s hospital excuse doesn’t justify ignoring consent—she could’ve sought other sitters.

For solutions, the sister should acknowledge her mom’s limits and explore alternative childcare options, like friends or services. The OP can keep supporting their mom while gently urging their sister to respect boundaries. Open dialogue, perhaps with a mediator, could ease tensions. Empathy and clear communication are key to mending this family rift, so consider a calm talk to rebuild trust.

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Here’s the comments of Reddit users:

The Reddit crowd jumped into this family drama like it was a soap opera, dishing out support and shade with equal gusto. It was like a virtual family reunion where everyone had a bone to pick. Here’s the unfiltered take from the community:

celticmusebooks − **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. NO ONE needed to take care of the kids. Their 'loving' half sister was with them.

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She wanted to be at the hospital instead of taking care of her siblings. What WAS absolutely 'cruel beyond words' was expecting your mother to babysit the 'affair baby' that broke her marriage and broke her heart.. NTA but you need to stop allowing your sister to bring up this subject.

pineboxwaiting − NTA Your sister didn’t need to be at the hospital. Her place was home taking care of the kids.. Sis is a drama queen.

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jellomonkey − NTA. Ask your sister why she didn't drop the kids off with your dad's new mistress. That ought to stir up some fun drama.

shelltrice − why couldn't she babysit at their house? she had no reason to include you or your mother.. what your dad did was cruel beyond words when he cheated on your mom - but she forgave him.. good for you supporting your mom. NTA

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Competitive-Bat-43 − Tell your sister that when her husband cheats on her and has children with another woman, she will understand.....I mean girls tend to marry men just like their fathers.. NTA

Fine-Virus7585 − Your sister is very insensitive and self-centered.. She was so wrong to try to push those kids into the mother.. Support your mother.. NTA. UpdateMe

No-Carob4909 − NTA. Your sister has absolutely no compassion or empathy for the trauma your mother and you have suffered at the hands of your father and his mistress.  She attempted to dump the products of that trauma on her, with no notice, without consent,

and had absolutely no respect for your mother.  As innocent as those kids are, they are nothing but a reminder of the betrayal of the person she thought she could trust and would spend the rest of her life with. . Your sister is a bad person. 

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CliveBixby1974 − Your sister is a f**king i**ot

VegetableBusiness897 − Good for you. There is no reason for your mom to take care of any strangers child. Their mom must have family, and surely there are friends and classmates of the oldest that could help out in an emergency.

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I get the feeling that while this was an emergency, your sister saw it as a potential easy win for her to get you abs your mom back into 'the family'.. 100% pure emotional manipulation.. Good for you standing up for yourself and your mom

Spirochrome − The most important thing for the father was probably the kids being taken care of, so he could be there for his wife/SO. No matter all the other stuff in these screwed up relations, she could've just cared for the kids to make things easier for the parents, no? Why would she have to be at the hospital this urgently and weren't there any other friends of that family that could take care of them?. NTA
Redditors mostly backed the OP, slamming the sister’s insensitivity while a few questioned her hospital urgency. Some threw in spicy jabs at the father’s role, but the consensus leaned toward respecting the mom’s boundaries. Do these fiery takes capture the full story, or are they just fanning the flames?

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This family saga shows how past betrayals can ripple into present conflicts. The OP’s unwavering support for their mom’s boundaries clashed with their sister’s pushy expectations, leaving a family divided. Whether you side with the OP’s loyalty or see the sister’s plea as a cry for help, it’s a reminder that empathy matters in family ties. What would you do if asked to bridge a family divide like this? Share your thoughts—have you ever had to draw a hard line with family?

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