I'll start this by saying DM doesn't see her H as being abusive. But he controls her in every way and can be really nasty. He is very manipulative, controlling and I do wonder at times if he even feels any emotional but anger and smugness.
As a parent myself now I can see he is abusive and his behaviour is not okay. They first started dating when I was a teenager and I found his behaviour towards me awful but DM defended it saying I was a difficult teenager.
He has been treating my 18 year old sister the same way as he treated me. She hates him as I do too. I've always told my DS she can stay here with me, I've the room, but she doesn't want to be too far from 6th Form, her friends or her job so she stays at her boyfriend's as much as she can. DM doesn't agree with how H treats DS but she says she is unable to confront him and often defends H's behaviour too by saying DS is "hardwork" and that H does provide a lot and is stressed.
However, this has all come to a head during a family gathering over the weekend at a pub. H picked up and threw DS against a fruit machine and then proceeded to attempt to attack her whilst she was on the floor. Thankfully DS has long legs and was kicking out. DM intervened and H was kicked out by security. Security suggested DS press charges as there is CCTV footage. DS doesn't want to as she is worried about wider consequences of police involvement.
DS is now staying at her boyfriend's and plans to stay there for as long as is needed (again I've offered my place too).
DM went back home to H who has been calling DM's bluff saying for her to go to the police as the CCTV footage will show DS slapping H first etc and attempting to gaslight DM.
DM is seriously looking into a divorce as she is agreeing this behavior is never okay but is also suggesting H could change and if he does get help then she could stay.
However, surely H should move out whilst he works on himself so DS can move back somewhere safe? H won't leave though, he also runs his business from home too, has an office attached.
I suppose what I'm asking is, how can I support DS the best I can? Is there anything I can do for DM? What should she know about divorce etc? Also I'm pretty sure H has control over all technology and devices, I know he has planted hidden microphones previously.