My boyfriend wants me to go naked on webcam for him..but i dont think its right!?

i and my boyfriend became friends on a social networking site...we have become close over the internet..we hav never met...but i completely trust him...n more importantly love him...we hav decided to marry for sure with our parents concern..now that i hav got a webcam..he is asking me to pose nude for him...but i am least comfortable doing it and more importantly i dont think its right to do so...i feel that it is against my culture...i told him innumerable times that i cant do it....but he is forcing me a lot..he is not taking food...he is falling ill...and wat not..i care for him..n i dont want him to fall ill...should i do as per his wish...or follow my wish and just not do it?