Domestic relationship

My brother is in a domestic relationship, he just called crying saying she tried to stabbed him and broke his car window. She is really crazy and emotional unstable person. She is 19 brother is 21.

They been together for almost 4 years, they have been toxic for as long as they been together. I know he won’t leave her. Should I call the police and report her or let him deal with it?

Thank you all for the response, unfortunately he isn’t ready to leave nor do I want to get involved till he realizes he deserves better. I’ll still be there for him and always has a room at our home.

He is okay now.