A couple things to consider.
The avenues for dealing with abuse are extremely limited in this society. If I have a close friend who is being abused by her boyfriend, there isn't much I can do about it personally. If I want to go over to their house and smash his face in, I can do that but I risk going to jail for assault even if I'm doing it to stop abuse and it has a high likelihood of actually stopping that abuse. I can report it to the police but they're not going to do much of anything without my friend's say-so. I can try to talk to the abuser but that individual has already shown problems with rational thinking, a rational discussion is unlikely to go very far and threats are more likely to escalate to a physical confrontation. I can tell other people but if my friend denies it out of fear of punishment, I'm basically crying wolf as far as other people are concerned. So there is really not much, if anything, I can do to help that situation directly. I can be supportive of my friend, offer her sanctuary, encourage her to leave, and as important as all that is, it still depends almost entirely on the target of the abuse saying something. This sets up the accusation "Well why didn't you report it sooner?" That puts the target in a situation where if they stay, they get abused. If they try and leave and maybe get help, they're going to be blamed for not getting help sooner and looked at as weak, soft, etc etc.
This leads into another point; abuse is almost always couched as a very male-centric crime. Its MEN that are abusers and never the targets. We don't see it as a hostile interaction between humans, we see it as something that a male does to a female. Even in my own prior example which I basically just pulled out of thin air, I assigned the role of abuser to be male and the role of target to be female. Granted we still live in a very patriarchal society in which most systems of power are controlled at some point by males and anytime you have an imbalance of power, the one with the lesser degree of power is more likely to be abused. Even taking that into consideration, we tend to think of abuse in terms of physical or sexual violence which is almost exclusively a male-centered domain, at least in the popular imagination. We often tend not to think of verbal abuse as abuse, its just being an asshole.
A further point is about the abuser themselves. Abusers are often reacting to situations of stress when they hurt others; a husband is stressed about work, he comes home and dinner isn't ready so he hits his wife, a wife is stressed because her husband spends so much time at work and she misses him so she verbally insults him when she sees him. They lack coping mechanisms to deal with strong emotions so they lash out physically or verbally at others and they're repeating patterns they've experienced while their opinions about the world were being shaped; someone who witnessed or experienced abuse as a child is at a much higher likelihood to be an abuser when they grow up. With that in mind, we should be conscious of how we handle an abuser. The overwhelming majority of people who are abusers are not sadists, they're not sociopaths, they're not actively trying to destroy another human being. Most of the time they dont realize the damage they cause in other people and they're unaware that what they're doing is against human dignity. If you immediately just exile people who show abusive behavior, a lot of the time you make that behavior worse because you've just ostracized them without any of the tools necessary to deal with conflict, frustration, stress, and relationships that they need to make better choices about interacting with other people. There are definitely people who have just learned too well that hitting someone or verbally breaking them down is acceptable and wont ever really be able to grasp the impact of what they're doing. But for every one of those, there are probably ten to fifteen other abusers who can be shown how much they're truly hurting people and can be helped to change their behavior for the better with proper interpersonal skills.
I am as direct as a T-Rex with 'roid rage and about as subtle. It isn't intended to cause upset, I just prefer to talk plain. There are plenty of other people here who do the nice, polite thing much better than I can. I'm what you'd call a "problem dinner guest."