I told my friend I can't be around her boyfriend anymore
Why don't you want to be around your friend's boyfriend?
I don't want to put up with her boyfriend's vulgar language.
It makes sense for you to tell your friend that you don't want to be around her vulgar boyfriend, because it's good to stay away from people that you don't like. I think you should try to avoid him but try to not let it affect your relationship with your friend.
Is it okay to break up friendships because you don't like that person?
I don't think you need to break up a friendship over it. Hopefully she'll realize he's not great to be around. But in the meantime, you can spend time with her without the boyfriend.