Advice/AITA/Wwyd/similar stories?

I guess I'm just looking for reassurance that I'm making the right decision. This is going to be a long read so I appreciate anyone who takes the time to read it, share any insights, or even offers a virtual hug tbh.

Myself (32f) and my brother (35m) have always had a great relationship. Our parents are divorced and have been since we were very young. Our dad has always been bitter, doesn't want to see our mum or talk to her, but they always put us first, never involved us in their drama or tried to turn us against the other parent. We have always come first to them.

Around 6 years ago my brother started dating a woman from overseas who he worked with. Very quickly she fell pregnant with my nephew (5yo). We were all so excited, he was the first grandchild in the family and we were all so happy for them. We were a close-knit family - always catching up and hanging out. This all happened during COVID lockdowns so it was difficult, but we did our best to make her feel welcomed into the family.

Fast-forward to 2021, they welcomed another boy into the family, and me and my partner had a girl 3 weeks apart.

When the little ones were around 8 months old we had to move house and it just so happened that the house next door to them was available to lease so we applied and got approved. My brother had also asked our dad if he wanted to move in with them. To help each other out financially and to be closer to the grandkids as he had lived interstate for most of our lives.

Our mum and I knew that this was going to put a strain on their relationship and the relationship between her and her grandkids because our dad did not want anything to do with mum. And of course it did.

My brother used to visit our mum most weekends and suddenly that just stopped. Over the next 4 years he stopped calling her, sending her photos of the kids or updating her on anything happening in their life. Which is very out of character for him. The only time she was able to see his kids was if *we* organized a BBQ or lunch and had to be at our house, or out somewhere. I became the middle man and it really upset me that he was able to push her away so easily and didn't care how it was affecting us.

His partner also changed. My brother always told me that I was welcome any time, but whenever I would go around she wouldn't even acknowledge me. I never felt welcomed by her anymore. I would bring my daughter around to play with her cousins and she would just ignore me. Not looking up from her phone and couldn't even hold a basic conversation with her. (Whilst my brother was at work). Whenever he was around she was a completely different person. Happy, smiling and laughing. If he wasn't there, she didn't even want anything to do with her own kids .. It's as if her mask was slipping and I was seeing the real her. She would also bring the kids around when they were sick and had fevers. Knowing my daughter had suffered from febrile convulsions when she got a fever. She didn't care. They never got the vaccine, didn't seem to worry about COVID etc. (This will be relevant a few paragraphs down)

For the longest time I thought my dad was getting into my brother's head causing him to push my mum away. But in all these years he has never tried to do that once. I quickly realized that it was his partner driving the wedge between them. There was *always* a reason they couldn't see our mum. And when we did get together they both sat there in their misery not saying a word, or just making snide comments.

To this day, I don't know why he turned on her and pushed her away. I don't know what his partner's motive is, either. I guess she doesn't have the same family values as we do, considering she moved across the world away from them..? Just wants him all to herself? Whatever the reason - SHE is the problem.

We moved out last year to the next suburb over, partially because the rent was too much for us. but also because I could feel the shift in our relationships.

Fast forward to last week. I stopped in for a random visit to see my dad. There was a COVID case at the daycare (that our kids both attended together, but she recently pulled them out for reasons that differ depending on who asks.. still not entirely sure why tbh) and the second I stepped through the door she greeted me by saying "Really?! COVID WEEK?!" .. My kids had not been there on the day the kid with COVID was there. They weren't sick, no fever, completely healthy. I just said "Wow. okay we'll just leave then..." and then she said "No, it's okay!".. Like why even say that then?! Didn't have that same energy when you'd bring your kids over with ACTIVE fevers, not telling us until they'd already been playing for an hour... very hypocritical behaviour.

During that visit I immediately noticed the amount of weight my dad has lost. Last year he was diagnosed with an autoimmune condition that affects him physically. I was the one who took him to the doctor, to get diagnosed and to his follow-up visits until he was able to drive. it has affected him mentally as well. He's not able to do the things he loves. Gardening, going to the pub, walking, cooking. And it's quite clear he is suffering from depression. Our dad will not get help, and I know that no matter what I say - he won't. So I accept that and show him that he has my support, that he can reach out if he needs me. He knows that I will be there for him.

My brother and his partner sat there and said the most vile things about him. Calling him lazy, miserable, useless and the list goes on. I was DISGUSTED. My brother claims to know all about depression but can't notice the obvious symptoms that my dad is showing? Not doing the things he loves, struggling to get out of bed, not going out, not getting up off the couch and not eating. It really has been hurting me. He said we need an intervention... and essentially put it all on me to fix it.. A HEAVY mental toll on me. And since our conversation last week when I burst into tears right there, he hasn't asked how I'm doing. He's just going about life as if it never happened with no regard.

But what REALLY pissed me off was his partner pretending like she's not the exact same way. She doesn't go out, she doesn't clean the house, she barely even parents her own children (who are absolutely insufferable because they've never been disciplined a day in their life). And my dad isn't allowed to say a word about it.

It's become crystal clear to me that my brother is turning his back on all of us. First my mum, now my dad and I can guarantee I'll be the next.

I've decided that I don't want anything to do with my brother's partner. After all that our family has done for her, having no family in the country we welcomed her into ours and treated her with nothing but kindness and she could not be less grateful for any of it. I'm just as disgusted with my brother, too. And I've come to terms with the fact that by cutting her off there's a good chance he won't bother making the effort to maintain our relationship. It hurts me, but I need to do it for the sake of my own mental well-being.

If you read this far, thank you. If you have any insights, similar stories, regrets, ANYTHING. Feel free to share.