please help...?

i am a 15 yr old...i am in 10th grade now...when i was in 8th grade i had a crush on this guy(say A)..in 9th grade he proposed to me..i liked him a lot but refused as i thought it would offend my parents(if they would find out)..now he is carrying on with his 2nd gal after me..but still flirts with me and says he likes me but had to move on..he says he lked me best..i am NOT able to get over him..he soo cute..but is known to be a playboy..like now he has a gal but still talks like this to me..i feel that he is betraying both me and his gal..how do i tell him..i think i still like him but will never carryon..(with him)

now of late i like this other guy(sayB)...when A foung out..he got very jealous and speak too much..i told A that i atlast moved on..he says good for u..he flirts too much like talks about kissing me and says i am very sweet...gets very physical like hold my hand..but is very upset as i like this B..i still like him but i dont wanna..what to do..i dont wanna hurt him.