Neither of us can understand why, if she’s left him, she’s still texting at all times of night.
With respect, this is why she needs professional help and not your brother. Because they would understand why she is still doing it.
A bit of personal insight, if it helps.
I grew up with mental and physical abuse. My dad was unpredictable and would 'go' without warning on a near daily basis. As a teenager, I would goad him and provoke him on occasion because sitting with the calm and the silence and not knowing if or when it was going to happen that day was unbearable. At least if I'd deliberately caused it, I was in control. Or that's how it felt at the time. I also knew that he felt bad afterwards sometimes and it also had to feel bad to him to be that angry and wound up. In my head, I was playing him at his own game. He made me feel bad; I made him feel bad. That was my power in the situation.
When I started dating, it was all I'd ever known. I felt safer with violent angry men than those who weren't because those who weren't felt false and like I was in a perpetual state of 'the calm before the storm' even when they weren't like that and the storm was never going to come. I was anxious all the time.
I provoked and goaded too. I dumped the ones who didn't react because the uncertainty was too much amd I just assumed they had no feelings for me at all. As bad as the violet ones were, I felt relief and it felt cathartic when it happened. Because I knew where I was in the cycle rather than feeling I was caught in limbo somewhere in the cycle.
That doesn't mean I liked it though and I would offload to people because i fel ppain and sadness and loneliness, and i also knew it wasnt right. But it was all I knew. It was the only relationship dynamic I knew.
I was in my 30s before I really understood that violence payed no part in any relationship and now I won't even date someone who raises their voice. But it took a long time and a lot of therapy to get to that point.
to use a metaphor. This woman isn't someone whose 'normal' was ever where yours and your family's is. So shes never going to get back to that. She's not even on the same playing field. She's playing a completely different sport on a completely different surface and with completely different set of rules and equipment. She knows how to play her sport - She's an expert at it. She doesn't even know the name of yours.