I don't know what to do please help?

i am in year 9 and i have friend in year 10 we have been friends for 1 month , we are together all the time ,one day his sister told me that he have a girlfriend i don't know but after i hired that i Start crying so i went to him and i asked him about his girlfriend and he said (yea i forgot to tel you about her) and he showed me her images and he told me how he love her ,so i dissed to go away from him and i could;nt tell him that i love him .the next day he came and he hold my hand and he told me don't go stay ,he love me but as a sister maybe i don't know he was going to cry he want me to stay with him ,he is making it harder for me to forget him , please help i don't know what to do all i thought that he love me but he got a girlfriend .