I have a friend like this, people are still trying to 'help' her after years of her throwing it back in their faces.
I'm happy to chat, meet up, go out but I will never get involved in her relationships because if her current abusive boyfriend were to die (and that's the only way to permanently rid of him), she would spurn every nice man around to replace him with a much nastier evil fucker. It is what she has been doing all her life and what she will continue doing until he someday gives her a hard enough kicking as to knock that nonsense from her, by that stage she will either be left for dead or seriously disabled.
One friend even put her up rent free for two months because of his threats to kill her and had to deal with him calling up to the house threatening to burn it down. She eventually went back to him, was seeing him while living in friends home and now friend is apparently a horrible person for being pissed for her being reunited with the scumbag of the century love of her life
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Your friend won't change. She's not a victim, she is an adult making her own choices. She loves him and everything he does to her. If he stopped in the morning she would find somebody that gives her what she wants. That is the truth. She likely loves the attention and sense of importance that being the victim gives her, I know my friend does.
You can still be her friend but don't allow you to drag her into her drama, it will likely end with you being branded the enemy when your support during a rough time is seen as interference when they get back to being lovey dovey.
She will never be helped until she decides to help herself, other people giving her attention will likely make it worse because it gives her the victimhood mantle and drama she wants rather than being forced to focus on what is wrong with her choices.
A love of violent men is like a mental illness, I don't think any normal person can understand it but being nice and helpful to somebody will not change their mentality, often it seems to reinforce it.