Brother getting married- should I tell her he's violent

[Mumfortoddler]

My brother has proposed to his fiancé. The last girlfriend he had, he gave two black eyes to and tried to strangle her. I did warn previous girlfriends he was domestically violent, but then basically every time they couldn't cope with his rages they used to call me. I tried to give advice early on to encourage them to leave, but they refused claiming they loved him. My brother used to abuse me as a child, beating me and trying to strangle me and sexual abuse, so its really difficult to talk to them in the first place let alone when his partners completely choose to ignore me anyway.
He's now proposed to his girlfriend of two years, at the moment there are no visible signs of violence. Part of me wants to believe he's turned over a new leaf, but I am not sure he has. He's forty and been violent from the age of 10 to 38, there seems little abatement, and his usual pattern is to get them into a committed relationship before he starts to be violent, so although this latest stint appears incident free, that's really only perception rather than fact.
I don't really know what to do- should I warn her?

I'm sorry for the abusive you've been through. I guess it depends - you've tried to warn before and it hasn't helped but it must be so hard to stand by and watch. What does your heart tell you?

yes tell her of course.

If you can I think you should warn her. She may not leave immediately- she may say she doesn't believe you. In the fullness of time though, I suspect she'll be glad for a little bit of warning of what might happen.

Maybe, if you can't face telling her the whole truth you could strongly encourage her to do a Clare's law thing with the police (if you know that they have information on your brother) that way she would hear facts from a more neutral source?

I think you should tell her, making it clear that you're not trying to break them up, etc. as I can imagine she might tell him and there could be repercussions for you and her, but in an "I care about you very much and I want you to know just in case" way.

Did he find out you had told previous partners about his violent history? What was his reaction? My concern would be that you could put yourself at risk. Does he still abuse you in any way? He sounds utterly vile.

My god, yes, absolutely tell her. But make sure you are safe yourself.

Absolutely. How awful for you op. I agree. Make sure you are safe yourself.

Tell her, but I'd be very surprised if he's avoided violence for two years. She's knows.

Does she have a sister or mother that you could tell instead? encouraging a Clare's Law application is a great idea: then it can't be dismissed as something you have made up or exaggerated

Definitely tell her.

I can see why people are saying tell her. But there is a good chance she just won't believe you or will think things will be different this time. I suppose you should tell her because if you don't and then things go very wrong you'll wish you had.

Has he been convicted of anything? Would a Clare’s Law check show anything up? Does she have a sister or mother who could usefully be tipped off?

From memory, I think there's a dilemma like this on Captain Awkward, with a really good response. Might be worth looking at?