My crush..im crying please help me?

i have a huge crush on one of my best guy friends and i was ecstatic when he asked me out. this is the only problem...we are both 16 and at the beginning of the school year my mom said i wasnt allowed to date this year. when i asked her when i would be allowed to date she said she didnt know. the night he asked me out (last week) i begged my mom to let me date him and she said NO DATING. im not allowed to go to boys houses as a friend! i would feel bad dating him behind my moms back so i told him no. i said i wasnt interested which he knows isnt true, but i would feel ashamed telling him im not allowed to date...i mean im 16! today i found out that he has a girlfriend he started dating last night. i cant STAND his girlfriend, very few people in my school can. shes annoying obnoxious and has bad hygiene...she smells, has bad teeth, wears dirty clothes everyday. shes also BAD news...smokes, drinks, gets kicked outta school. im nice to her just for his sake but everytime i walk by them in the hallway i feel ashamed i feel like a huge loser. please help me!