Worried my DB is abusing my SIL

[Elevader]

For background: DB & SIL have been married for a year. I see them a couple times every year. There is a fairly significant age gap between me & DB.

Today there was a gathering, and I escaped to another room for a while unnoticed. Later, I heard SIL crying & sobbing. Then my DB came up and was doing that sort of hissed shouting? I couldn't hear everything but I did hear 'you're fucking useless' and she kept apologising. DB went down again, so I knocked on the door, asked if she was alright etc. SIL told me she was fine, and not to tell DB I heard anything. That statement was incredibly alarming to me. I'm concerned that DB is emotionally abusing my SIL, with the possibility of violence too.

I don't want to confront my DB immediately, as I'm concerned that could make things worse for her. Does anyone have any advice of what I could say to SIL?
Apologies if this is the wrong place to post this.

Are you close to your SIL - could you take her out for lunch, say and get an idea as to what is going on? From what you've written, sounds bad but it could be an isolated incident? You mention the age gap - so are you and your brother not close? Tough situation...

You could also refer her to Women's Aid - just along the lines off 'if you ever need to talk, you can come to me or if that's awkward, try WA?'

I'm concerned that DB is emotionally abusing my SIL, with the possibility of violence too.

Unless there is a back story, I'mean not sure you can assume that from what you have said and only hear a snippet of an argument.

It is tough situation. As pp has said, maybe ask SIL out and gauge the situation.

*I'm not

You are his sister. I'd be amazed if you are wrong as you will know his reaction pattern well.

What had set it off?

Was there abuse in your home growing up? Angry father or perhaps an overly critical mother?

Sorry to dripfeed but I wasn't sure if this would be directly relevant. DB and our father clashed greatly years ago, culminating in a lot of abuse. At this time, both my dad & DB were prone to flying into rages which often escalated into physical violence. I think I'm especially sensitive to what I overheard because I'm scared my DB is emulating our dad.

To add context, I'm 15 years younger than SIL. I've never seen SIL in a situation without my DB. I think I will try to engineer a moment where we're alone as the gathering continues tomorrow and I'll do what StopLaughing said. Thanks to both of you

Sorry, I took a while to post. Yes it was an angry father and the way DB was reacting reminded me of him. I reckon that's what caught my attention immediately.

I don't know exactly what set it off, but it had something to do with SIL 'embarrassing' DB. I'm skeptical that she actually did anything, considering that in all the times I've met her, she has been lovely.

Ok if he grew up with abuse then I would say there's a strong chance he is being abusive.

I doubt you have much chance of changing him. Reaching out to your SiL might be a good idea. Offer your support. She may or may not accept.