Mom and dad arguing

So my parents got into a huge argument tonight. My dad as always yelling and cussing hateful words to my mom. I was suprised that she wasn't arguing back. Things got quiet and then I heard her tell him that she cannot take it anymore. She told him that he's changing her, and she's starting to hate him. Hearing that has scared me...what exactly does she mean? I don't want my parents to get a divorce.