Please answer! Im so confused!?

Ok i have liked this guy since the 3rd grade! Im sick of playing the little flirty games. I wanna tell him so bad so i was like so close to telling him then he started dating this girl that i cant stand! Shes so annoying! But anyway we still flirt a ton! He talks about dirty stuff to me and asks me questions like who i would do haha and who i like and what he has done and what he wants lmao and he sits behind me in global and hes always acting like he is drawing on my back and messing with my hair and he did jumper cables to me one time but it was more of a grab my waist then a poke haha it seems like we have so much. He talks to me when ever he sees me in every cl when were getting picked up from school in the gym every morning but i have no idea what to do and how to get rid of the annoying tramp because i know he doesn't like her. He seems so bored with her. So can anybody help me please :)