AIO — I told my mother that she should get less involved

My brother started dating a girl from a different country while she was studying in ours around a year ago. This girl, I’ll call her Hanna in this post, doesn’t speak any English or our native language and has a pretty different mentality judging by what my brother told us. My mother wasn’t too thrilled about my brother’s choice and they had some big arguments when she’d ask him about his personal life and he’d just refuse to say anything (in my view he was overreacting as she never really said anything very mean then, just wanted to know more about the girl). Hanna plans on staying for a while in the country and find a job, but her father insists on her coming back to her country straight after graduation in June, which she does.

After that, she finds a job in her home country and doesn’t really make any plans to come back, my brother ends up buying her tickets for her holidays so she can come visit (he visited her there earlier in the year before that).

Fast forward to November. Hanna comes as planned and it turns out that she has hepatitis and she’s had since her early childhood. She assumedly only told my brother (that’s what he’s told me but isn’t quite sure about it) about it because her father made her do so). My brother is in absolute shock, takes tests and luckily he’s clean. My mother cries for days over this (she’s always been very protective of us). They have a talk about it around that time and from what I understand my brother tells my mother that he’s no longer considering dating this girl.

Now some more time goes by, we’re now in January. My mother asks my brother if he’s broken up with Hanna yet. They get into a major conflict with him telling her that it’s none of her business. From my conversation with my brother I understand that he’s not quite made the decision yet but he feels that my mother is pressuring him. They sort of make peace but don’t really talk about it.

Now comes today, I am at my parents’ house, go downstairs and my mother suddenly starts talking to me about all this. She tells me that she is going to straight up ask my brother if he’s aware of how dangerous hepatitis is. I try to explain to her that it’s a very bad idea to approach the problem like this considering how sensitive of a subject it seems to my brother. My mother refuses to listen to me and throws a tantrum that I “do not support her” whereas all I’m trying to do is to prevent an even more massive conflict. She yelled at me saying she didn’t expect anything else from me and that I don’t care about her. At this point, I told her that my brother’s relationship doesn’t concern her, at least not directly, and that she should trust him to do what’s best for him.

I think it’s awful that the girl gif something that could have cost my brother his already fragile health, I don’t see her as a good partner either but at the same time I feel that my mother is getting involved way too much into a relationship between two adults.

Do I just walk away? P.S. My brother’s 33, I am 27, Hanna is 24 and my mother is 62.