I'm moving on,but..am i doing the right thing?

so,i was dating this guy named david...i had with him;;he was my first. /: i'm moving on... well..i'm startin to like this guy named adam,but..him and david are really good friends..well,i was texting adam and he was like "so..." and i was like 'ugh,i have valentines day commericals..i'm always single on valentines day.. /:" and he was like "well.. :)" and i was like "well what?" then he replied saying "idk,u tell me." sooooooo,i replied saying "are you saying we could date?" he said "yea." i was happy.. and replied "do you want to?" he said "idk,if we do..we cant tell david.but..we'll talk about it tomorrow,come over..gtg" i've known adam foreverrrrrr , and david..me and david were really close..we always break up.. and go back out..same with me and adam. but,why would it matter to david?? he said he was only using me for (apparently) but;;before..me and david had a talk..he said "i wanna be wit u,i just dont like the fact that all we do is have ." i told him that can change,well..his dumb decided to call a quits.... but..why would it matter to david that i would be dating adam? help? i'm so confused..