Of course this happens!?

I had a boyfriend..for about a year and then we break up..knowing its time to move on..so he dates this other girl and i date another guy..and then.. at school my class gets switched so i have a class with him and not only that i get switched to his lunch...AND they made it so i sit RIGHT next to him..it was really awkward at first..and then he looked at me and started staring. i first pretended to not notice..and then i look at him..and he has these big eyes that make me love him even more..and he looks sad..and that hes missing me..he stopped and then later he passed me a note like saying what amm i doing in his class and that we werent supposed to see eachother..he was smiling but he kept saying i should get out of his class..i keep saying i didnt have a choice..and then he started saying stupid things? like he called me a bit*h and then said he was just kidding and then he told his new girlfriend to kick my a*s but he was joking and said it across the room..just i dont know what to do.. i mean of cours ein his class right next to him!