If your brother really cares about you, he'll want you to be happy. Introduce your bf to him over dinner. Cook a nice dinner and let them get to know one another. Ask your bf if he has any of the same interests as your brother, to keep the conversation going. Good luck.
P.S. You need to stand up to your brother and let him know you are capable of making your own decisions and mistakes where boyfriends are concerned. After all your brother isn't exactly in a position to question anyone's judgement regarding bf/gfs.