One should fight to stand in good accord with one's own conscience. Fear can weaken the resolve to fight. Avoiding conflict regarding an important principle can be cowardice. Inaction at the time of necessity is inexcusable. The first rule of nonviolent action is to refuse to cooperate with any action that is humiliating.
Verbal abuse is always humiliating as it is nonrespectful towards the other person.
When you are being screamed or yelled at, leave the situation, noting that you will return when things have calmed down. Noncooperation can be a potent force helping to disrupt verbal abuse. According to Gandhi, you can engage in nonviolence even if the other person engages in war. Pressure techniques such as strikes, boycotts, and demonstrations to gain attention for your cause are permitted. Go ahead and fight with the principles of nonviolence acting as if the person were pleasant, generous and flexible.