Instead of meeting a verbal attack with another one stop, think, and listen to what the other person is saying. Allow yourself to relax and focus on what you want to achieve here. If the other person is trying to get you to react to them, don’t. Relax and detach yourself instead. Being clear about who you are and what your own motives, desires, and feelings are, will help you.  Meditation and reviewing your boundaries are good exercises to start this process.