Trouble with my boyfriends best friend? Please Help me!?

My boyfriend and I have been together almost 2 years now. We've had some trouble in our relationship for about the last 3-4 months. My boyfriend lied to me about going to parties and drinking, I have since forgiven him, because I think everyone deserves a second chance. I noticed he started getting into these old habits when he began to hang out with this guy, Adam. He began to lie to me and want to go to parties and drink again, which he hadn't done since we began dating 2 years ago. I know I can't blame his friend for his doings, but I feel he does have a great influence on my boyfriend. He's trying to go to college and make something of himself, and this friend is a low-life druggie that sleep all day. When I found out my boyfriend lied I broke up with him, he asked for my forgiveness, so I forgave him on one condition, that he wouldn't hang out with this guy or go to parties or anything of that sort. This so called friend of his is rude to me when I call, he won't tell my boyfriend that I've called, he laughed at me one time when I thought my boyfriend cheated on me and made it seem like he did, all around he's just a rude person that doesn't respect our relationship, he want my bf to be single and hang out and play video games all day. My bf moved in with other friends now and this guy is always over there, my by can't really do anything about it because the house is in another one of his friends name. I noticed that my bf is starting to forgive him and hang out with him again, I don't know what to do about it? I don't want to tell my bf who he can and can't hang out with, but I honestly don't think this guy is a true friend and he's rude to me, I really need help in what to do? I don't want this guy to influence my bf anymore, because he's trying to do better.