He would be a fool to have you arrested. If he did that his abuse would come out in the open. Sometimes, when, in emotional turmoil, we do things that are out of character for us. Forget about it. It is not as though you took a baseball bat to her.
IF you are concerned about the kids, you can call child protective services and they would launch an investigation. I would try to stay out of the home there and do your own thing. IT is too much to deal with.
You cannot get her to get out fhte home. she has to want it. It's hard.
Have you ever read about codependency? I used to live with an alcoholic spouse and sometimes I would fight him to try to get teh alcohol out his hands. Crazy I know to peopel who havce not been there, but living and trying to change people can get us really doing things we don't normally do like hitting sisters out of anger, etc.. It can make us almost insane as we get caught up in the quest to change others.
BRILLIANT ....... hey PM me
Well we took the house but not the senate. I voted! How are you feeling today.
the answer seems to be yes he can ....
You did the very thing you accuse her husband of doing, so in her eyes, how credible are you? You abused her and are not paying her bills either. Unfortunately until she sees the problem and wants to do something about it, you will simply be a meddler in her eyes and she will protect him all the more. She has to want out before you can help her. As far as you hitting her and him having you arrested, no I don't think he can do anything but she can. Be careful with your good intentions because if he is abusing her, your actions could make it worse for her. At the very least he will make her break all communication and then you will have no knowledge of what is going on. In time she will need you and it would be good if u are there for her to turn to, but it has got to be in her time, not yours.
Hitting is no different to what you are accusing your brother-in-law of doing although I expect it was more out of frustration than anything else.
If a formal complaint is made then I expect the police would need to investigate it. I think some sort of complaint would need to come from your sister though.
It sounds like you need some professional advice. Is there an agency or organization in your area that you could turn to for support and advice?
You could perhaps try the abuse support community forum as they may have more ideas.
If you're really stuck I would talk to your family doctor.