I'm going to make my boyfriend stop talking to his best friend for good
I'm not really sure why you think that he should stop talking to his best friend, could you explain?
His best friend is a bitch who just shits on everyone
If you have a problem with a partner's friend, then you should talk it over with your partner.  You shouldn't, however, just straight up tell them who they can and cannot talk to.  That'll just create relationship problems.
So I should put up with a bitch who is constantly trying to ruin my relationship.
Yes, you should put up with it to a point and also let your boyfriend know how his friend makes you feel and that you don't like it. Maybe he will invite him over less or speak with him personally about his treatment of others, and then you don't need to force your bf to choose between either of you.