I'm the only Muslim in my school and am forced to take the kafr as friends, how should my relationship be towards them, is it permisible to be their friend?

There are three categories of associating with people:

1) Mu'aamalaat (dealings)
2) Muwaasaat (kindness)
3) Muwaalaat (bosom friendship)

Association of the first and second categories (dealings and kindness) with the kuffaar is permissible. Rasulullah Sallallahu alayhi wa Sallam was very kind and polite with the kuffaar. He also contracted business dealings with them. However, Muwaalaat (bosom friendship) with the kuffaar is strictly prohibited as that may be detrimental to one's Islamic values and principles.
Detest very strongly the evils of the kuffaar but do not hate them personally. Strive to influence them towards Islam, but never be invited by their way of life. Always adorn your heart with the consciousness of Islam being the most superior way of life , and that there is no reason at all to feel inferior. Win over the kuffaar with good character, yet never compromise the principles of Deen. May Allah Ta'ala make us all true inviters towards Islam.

And Allah Ta'ala Knows Best,

Mufti E. Desai