Best guy friend likes me..

my best guy friend likes me.. but I dont like him…well it all started this Thursday when he came up to my desk & said to me “I love you” I really didnt belive that because we always joke around like that… people always tells us”are you two going out?” and I would say “no” but people would say”he tolds us you did” … I really got mad at him for sayinq that because I like this other guy in 8th grade & im scared of him finding out that lie.. I already told him to stop spreading lies.. he says okey.. but minutes pass by & he starts again! really that last straw happened when my other friend(girl) told me to go out with him! I was like”your kidding me!” & he told me in MY FACE that he loved me! I felt really sorry for him.. but I only see him as a FRIEND..my friends even told me that if I didnt go out with him they wouldnt talk to me anymore! then they told me “at least give him a chance! he really likes you! go out with him for at least 2 weeks!” I said ok but during that winter break weeks & they said no that when we come back… ireally DONT like him…I love someone else.. then today(friday) in the morning I told him I was going out with someone else.. and he got really sad.. then he said it was okey that we can still be best friends.. but my friends tell me he still likes me.. what should I do to make him understand without ruining our friendship? plzn help!