Me [23F] with my brothers [21 M & 25M] knew our father was cheating on our mother and never said a word.

A week ago I found out my dad had been having an affair for 3 years now. I only found out because he annoyed someone in the community who knew and spilled the news in revenge.

There's 4 of us all together, 2 girls and 2 boys.

The boys found out the their father was cheating on 2 years ago when they logged into their father's laptop and found emails and FB messages.

They apparently confronted him about it and he promised to stop but never did.

The 21 year old still lives at home with my sister 20 and the 25 year old only moved out last year. My mother has been a SAHM for all my life, doing everything for us. The thing is, she's far more intelligent than my father but unfortunately is a product of gender roles of her time and culture. She has raised myself and my sister to be far more independent. Her father married her off to my father because my grandfather had done my father business favours and he wanted to see his daughter married off as she was "getting old" i.e 23.

When my mum confronted their father he basically told me that it was over with that woman and he wasn't leaving the house since he paid for it.

My mum is staying at her sister's. My sister and I packed up our things and moved with her. We're not speaking to our father at the moment.

The 21 year old still lives at the house. I can not bear to speak to him at the moment. He keeps calling me, in tears saying that the house is in shambles but I just hang up on him and so does my sister. He probably just wants my mum to cook and clean for him since he's lazy and does nothing around the house.

The 25 year old, my mum told him she was dead to him and to never contact her again when he called. He calls me every day though apologizing and we both end up crying on the phone. My sister and I so far have told him not to come see our mum. She keeps saying she doesn't want to see him but he wants to see us.

I feel so lost. I don't know what to do. His family keeps calling my mum telling them to reconcile, that she's too old to shop around, that she's neglecting her children which makes me furious.

Right now I don't even want to speak to my brothers or my father. He has called me twice yelling at me and my sister for being ungrateful and moving out and has threatened to cut us off financially. I am furious at him but I also feel like a bad daughter since he did support us all these years.

I have a grad job that pays well and my sister is currently studying and working part time. My 25 year old brother wired me some money but I just sent it back to him and he got upset.

My dad and I never really had a relationship, he is a lot more conservative than me and also paid more attention to my brothers. My mother was the one who valued our education- for example paid for my brother's tutoring whereas my mother tutored us herself and would often scour the Internet for free worksheets and videos and things.

She even took on a few dress making jobs and sent my sister and I to an automotive maintenance class and DYI courses at the local hardware store because our dad didn't bother my sister and I.

I have no idea how to deal with this. I want to support my mum. Should I cut off my brothers?

TLDR: My brothers knew our dad was cheating on my mother and said nothing. I am furious with them and my father.