Dealing with a narcicistic person

Hello there!
After reading several articles about narcicism I have concluded that my sister's husband may be experiencing this personality disorder. I am facing a depression disorder and am currently on medication and psychiatric treatment. However, when we get together, people that are inferior to my brother in law (like myself) are subject to his constant criticism, comments, sarcasms and harrasment. Nobody seems brave enough to say something to him... What can we do? What shoul I do? Should I continue evading him?
Thank you for your support!
Marta Vitols

Yes, continue to evade him.

Read more about personality disorders.