My Boyfriend's Cat

My boyfriend has this cat who is such a fucking asshole. He scratches and attacks for no reason. The only people he's decent to, is my boyfriend, his mom, and children. And by that I mean he won't attack children. He will just run away and hide from them. He's an ugly mean fat cat but my boyfriend has had him since he was a kitten. He's 6 years old. I really want to move in with him, but he refuses to get rid of him. We've been together for nearly 2 years and that cat still hates me. I really want to live with him, but not his ugly mean fat cat.