I'm going to a very liberal college in Boston. Coming from the conservative south where I'm closeted by my family and friends (you should hear the things they say about homosexuality, they truly are terrible) I don't know what it's gonna be like to be "out". I'm not going to closet myself in college, I want to be able to be myself. Also, my super homophobic best friend (I've known him for maybe 9 years now) is also going to a school nearby, and I don't know how to deal with that either...
In college, no one will really give a damn about your sexuality. Just be yourself in college and you will be absolutely fine, join the GSA at your school. Boston is a very liberal area so I wouldn't care so much about the surrounding area. Just be yourself and you will be happy If your friend is truly your best friend, he should be able to understand no matter what. Best friends are supposed to stick by their friends despite differences.
In big universities, small liberal arts colleges, and colleges in cities and liberal areas, your sexuality is a non-issue. That's a big chunk of the colleges in America. As for your friend, take it as it comes. Whatever you do, don't let it affect your studies. You might want to stock up on some new friends prior to broaching this to soften it going south, no pun intended, should that happen.
You're going to have a ball. Instead of worrying so much about your sexuality, your goal is going to be how to NOT be a slut. Lol. Kidding, but foreal! There's so many options. You start dealing with other people a lot more than yourself and things can get wild when you're doing that. I'm excited for you! It's a great place to widen out and figure out who you are now and who you want to be.