It Takes A Couple Seconds To Say Hello,, But Forever To Say Goodbye!!

okay well i really like this guy.. but my best friend likes him or liked him,, she says she doesn't anymore but I'm not to sure..he knows i like him and he said he likes me.. but if my friend still likes him i don't wanna do anything to hurt her but i cant stop thinking about him and i don't know what to do... i need advice... HELP!!!