A huge argument with SIL

I need your opinion on this. My SIL is 10 years younger than my husband, so I basically witnessed her growing up. Now, she is married and expecting a baby. She always insults my husband before my eyes and they get into heated arguments. This has always been odd to me because I have a pretty peaceful relationship with my younger siblings. So, fighting with me in my husband's presence is something unimaginable.
Today, there was another argument between my SIL and my husband and for something insignificant. She was cursing and calling really nasty words. I couldn't hold myself and got involved. It has always upset me that she would not respect her older brother. Now, she hates me and my husband. Did I dp the right thing trying to defend my husband and telling her she should not call him those bad words?
I'm 35 weeks pregnant today