It's good to have people disagree with you from time to time. First, it's important to know what disagreement feels like, and it's also important to notice how different types of disagreement affect you.
There's respectful disagreement--disagreement that comes with polite words, constructive ideas, and a willingness to work together to find common ground. This is positive and productive disagreement. Then there's the kind of disagreement when you feel backed into a corner as either the one who disagrees or the one who is hearing the disagreement. When backed into a corner, you may want to lash out.
I've been in all of these positions at one time or another. Respectful disagreement is truly productive as people work together to make better, compromise, find common ground solutions, while backed-into-a-corner disagreement is frightening, worrisome, and even dangerous at times.
Once when I expressed disagreement from a backed-into-a-corner position, I used harsh words, facial expressions, and body language. I was angry. After many attempts to change a situation, I was met with more oppressive obstruction--I felt backed-into-a-corner. When systems, structures, and environments are oppressive, people often feel backed into a corner, and it is very difficult to be reasonable or thoughtful in that position, but of course, it is the right thing disagree with respect and peace. When backed-into-a-corner, you have to find groups outside of the oppressive situation to help you--groups that work for the ideals and dreams you hold. Those groups can help you to find your voice and work productively and peacefully for change.
When you face the disagreement, hate, and anger of someone who is backed-into-a-corner, that's scary. Their words and actions may frighten and alarm you, and you may not know what to do. You have many choices in this regard. First, it's important to make some space between you and the individual--don't egg them on, but get some space to think about what's happening and why the individual may be backed into a corner. Then, figure out a way to reach out, help, and hear the whole story. That may be difficult or impossible to do on your own, and you may have to get help from others to do that. Show compassion, but also safeguard yourself too. If you've hit a raw nerve in someone who is feeling oppressed, alone, annoyed, bothered, or troubled, they could erupt in dangerous and destructive ways so tread gently and don't go it alone.
There will be disagreement, and those that handle disagreement with respect, grace and a will to understand what's happening and work for as much good as possible, handle that disagreement in productive and positive ways. Onward.