Hes such a creep PLEASE HELP?? XXX?

i am 16 and for a few months now this 21 year old has fancied me. he keeps texting me telling me how desperate he is to go out with me and im scared. he is a friend of by best "boy" friend so i cant be mean to him because my friend may fall out with me. he is tall spotty and wears glasses and he is definatly not my type. he stares at me and whenever we are both out at this friends house he will start singing songs that have sex references in them and aim then at me. when me and this "boy" friend were on facebook lookin at some pictures of my leaving ceromony at school he was stood behind us going, "very very nice". he is a nice lad but i dont want to get with him and i have told him so many times. he has also told me that his little niece has been diagnosed with cancer and is so upset that he wants to cry in my arms. i dont know wether to belive this or not. he is just not my type and he is too old. how can i get rid of him and make him leave me alone. he is creeping me out!!! can anyone give me any advice??? xxx