A guy from my class seems to like me - and I am not into that

First of all, do not get me wrong. I am a supporter of homo sexual relationships.. As long as it doesn't include me. I've had some episodes which have rendered me somewhat of a homophobe when it comes to guys being interested in me. Some background story could be in order. I'm 18 and attend to something called a gymnasium in my country (3 years prior to university), which is a science and technology-oriented line of study, and therefore it has a lot of guys in it. Now I decided to go to the nerdiest of all of the different subjects you can have, and this specific class apparently often has a lot of homosexuals. I have no problem with that, as mentioned earlier, except that I am thin and good looking, and in a way a very small part of feminine looking. This has been a problem with my look on more occasions, but this time it's worse. I'm good at reading people's body language and emotions, so I can naturally and unfortunately very easily see when a person is interested in me. This guy from my class, who I only recently noticed kept sitting besides me and leaving at the exact same time as me. It makes me feel extremely uncomfortable, and I have a very strong tendency which have followed me throughout my entire life, which is to blush when I feel either uncomfortable or begin to be self conscious, which can even lead to random blushing with no real trigger. I don't know how to deal with this guy, and he's seriously just making my days very hard, which he of course doesn't intend to, so I have no real hate, but only the very uncomfortable feeling. Help on how to tackle this preferably without anything awkward would be much appreciated!

If he should tell you "I like you." You can then tell him "you are straight". But life is not a straight line :-) Things are not always straight-forward. Have the two of you started any conversation yet? If yes, indicate "you are straight" as and when the opportunity arises. If you have a girl friend, use her photo as your bookmark. When you have a chance, like if you see him glancing/looking at the photo, smile and tell him "She's my girlfriend." :-)