Boyfriend with horrible best friend?

I've been seeing a guy for seven months now, but he has his issues. He has a best friend (ex-convict for domestic abuse) who he goes out to drink with at bars. Boyfriend has decided he doesn't want to tell me when he's going out with his friend because it makes me mad. Frankly, I don't think his best friend is the best influence for him. When we're face to face, his friend treats me as if I'm either invisible or too stupid to understand a human conversation. I think this is because my boyfriend has told him everything about me, including things I asked to be private between us. Boyfriend nearly worships this guy and follows all of his advice, including when the guy tells him to ignore me! I'm afraid his friend is ingraining into his head that I'm bad for him, and I think the cause of this is because best friend wants boyfriend to be single and prowl around for women with him. My first introduction to best friend was of pictures on my boyfriend's phone of slutty women all over both men, so I haven't liked this guy from the start. I don't know what to do about this guy because my boyfriend thinks he's God's gift to friendship, but I think he's driving a wedge between us. Every time I say something, boyfriend makes it out to seem like I'm just jealous of his friend. I'm at a loss of what to do. Help??