I'm going to expect my boyfriend to stop being friends with a girl I can't stand
Why can't you stand her?
She's a bitch, she makes fun of me in public, and is very snarky to me all the time
Those do sound like valid reasons to stop being friends with someone, so I hope you're just not jealous. It wouldn't be right if you're trying to interfere in a friendship. I think you should tell them how you feel before making a decision on how to act.
It would be sort of stupid if I was jealous of this person and would never be that petty but yeah I'm going to try to break them up
It is rude to hurt other people because you don't like someone. Have you thought it might backfire and you could end up the one friendless?