So confused

Ok, so obviously I am a complete bitch and I think that by the end of this it will be apparent but I have no clue what to do, my head says one my heart says the other, ok. I have been dating my boyfriend for just over two years now we have had the best time holidays spending time together, living together but we just don't seem close and even when we do try and talk its alway harsh and I actually never know what to say to one another. We chill out with a substance that I have never been involved with before I was with him and just don't want it in my life but it has been part of his life all his life that I can't make him give it up. I don't know how to talk to him and its dragging me down. Then there's the other guy, I've only known him 6 months but I feel like I've known him forever we get on so easily and I can talk to him it feels about everything but we only see each other once every month maybe outside of work to be ourselves, sometimes it's awkward but I really like him and being around him, I just can't make the decision and its killing me and the people I'm around.?!