As one who has been in that situation myself, you have my strongest sympathies! Hold firm to your conservative beliefs and don't let them intimidate you. I was in your shoes four years ago when I was choosing where to go and witnessed it again last week in conversations with a brother who just started his freshman year at a left wing school. I can give you the same warnings and advice I gave him.
First, it is an indisputable and inescapable fact that fringe radicalism runs rampant on modern college campuses. Many are sad shells of their former academic selves, having long since adopted entrenched and systematic forms of Jacobin indoctrination in place of the pursuit of knowledge. I did my undergrad at a university that, fortunately, was not among the worst and actually had a few conservative departments. But there were also lots of leftists pursuing off the wall leftist activities, classes, and programs. The worst element is also one that is common to most if not all modern colleges - the relentless adherence to and evangelization of a "diversity" religion. "Diversity" is almost always the name that they use to peddle the homosexual/reparations/mohammedanism/affirmative action/terrorism/environmentalist/tolerance crap that appears so frequently on campuses. This has worsened immeasurably and noticeably in the last few years alone. I applied to several universities during my senior year of high school and got freshman orientation packets from each. Some of the schedules had "diversity" lessons - included among many other campus basics - on them to be sure, but when I saw my brother's orientation schedule last week I was in shock at how much it has come to dominant freshman orientations. It has two lengthy classes on so-called "multi-cultural" training and consumes more space than probably any other topic in the orientation handbook he got. Each and every dorm now has its own "diversity officer" living on site on top of an official campuswide "office of diversity" in the adminstration building to fund and promote things like the homosexual activist program your school also has. Most schools now require or heavily emphasize some sort of "diversity" or "sensitivity" training seminar for incoming freshmen and portray them as harmless and beneficial experiences rather than the subversive propaganda sessions that they truly are.
Second, once on campus find yourself a conservative student group and get involved in it immediately. You should also get on the Young Americas Foundation mailing list - they're a conservative group that specializes in providing support material, books, and speakers to the conservative minority on the worst college campuses. Also figure out who and where the conservative professors are as soon as you can. There normally aren't many, but there is always a small handful - often holding out in an enclave of a single department or two. Ask the older students in your college republicans who they are, take their classes when possible, and introduce yourself to them. That should help you hold out for and survive the left wing freak show that is college.