Please help, I'm caught in a predicament between my boyfriend and best friend and don't know what to do?

So I just started being friends with this really awesome guy about six months ago, and we started dating about three weeks ago. After literally a matter of days after dating he said that he loved me, and then apologized since it was so early, but I thought that I felt it so I said it back. I still don't know if I really do, I really thought so until my best friend of 16 years came back from being away for a year. (We're all 18 by the way). I've kind of always known that he liked me, and he apparently confirmed it to my family when he was visiting over Christmas break. I was dating someone else at the time, but this guy he did not approve of (and had reason) and told my family that he was planning on finally working up the nerve to ask me out when he came home, but found that I was dating someone. He then told them that he was coming back home because of me. I have always been very closed-minded to the idea because we've been best friends for almost our entire lives, and so I put it out of my mind. As soon as he came back last week I started to feel different about him, and about my own boyfriend which I feel absolutely terrible about. My family loves this guy, but they also love my best friend and have wanted us to get together forever. I just feel so bad because I've only been dating this guy for a short amount of time and was fairly certain about him until pretty much the moment my best friend came back. What do you think about this? I really don't want to cause any hurt :(