You can just say, "I don't like what you're doing and I don't like it to the point where I'm not going to be around it any more." Whether not being around it means for the next five minutes or next hour or next day or the rest of your life is also totally up to you.
If someone is truly, knowingly being abusive to you, then this comment is not likely to have much effect. An abusive person either 1) does not realize s/he is being abusive, 2) knows s/h is being abusive and doesn’t care, or 3) knows s/h is being abusive and does care.
Case 2) may not be so bleak if that person is angry, hurt and in denial, therefore thinking s/he doesn’t care when s/he really does. So for all 3 cases, it is possible that the abuse is just a cry for help, attention, validation, etc, right?
So what will saying "I don't like what you're doing and I don't like it to the point where I'm not going to be around it any more" do to resolve the situation? It might work in case 1 & 3, but not in 2. Then you are faced with following through. So what will you do then? If you feel that person is abusive, and you are trying to be civil, an imbalance already exists and your statement might be a little late and sound like an ultimatum of sorts, and could lead to escalation.
IMO, if you ever have to tell someone else that you will not tolerate such-and-such behavior, then you are already in deep sh*t, and that is as much your responsibility as the other person’s. Better to track the pulse of the “balance” in the R to be sure the above situations does not develop.
