My best friend is rude to my boyfriend

Lately my boyfriend has been having a really tough time at home and it’s been affecting him. He’s been distancing himself from me and other people. My friend knows that he’s going through a hard time and is always calling him rude names. She says that he should go die in a hole. She’ll say “this is why I don’t do relationships” and other things like that. It gets me mad on how she keeps calling him rude names and tells me that I should just break up with him. He’s really hurting and she knows it.