I'm so confused by him, please help?

I have been dating this guy for a long time *two years in april* and i am starting to wear thin. One of his friends from his hometown just moved in with him and his roommate, and he is driving me crazy. He is super annoying, thinks hes right about everything, makes stupid comments, always says that I don't know what I'm talking about, one time he actually told me that my opinion didn't matter because I "don't watch enough action movies". What is that about? And he gets my boyfriend to do stupid stuff, like my boyfriend got in a fight recently, and I tried to get him to walk away, that it was not worth it continuing, and the friend just egged him on said I needed to get out of the situation. I'm starting to get pissed. And lately, my boyfriend has not had enough decency to stand up for me in these situations. He just laughs along with his friend or agrees. He walks in front of me, doesn't hold my hand as much, and my opinion doesn't matter. I am so back burnered it's driving me insane. I don't know what to do. I am not being possessive or clingy, this is just new and confusing behavior that I don't feel like putting up with much longer. Please help me.