Need help?? Really conflicted! Should i o after her?

Ok so theres this realy close friend of mine that im starting to really like. Weve sorta been flirt lately but im bnot sure if i should go further since she also used to go out witj one of my close guy friends who (which is why her and i got close) they broke up cuz he moved away. He also told me other day that he may want to still get back with her but in 4 years.. Which is kinda wierd in y opinion. Soo im thinkin that i j try anything either she'll reject me cuz of that.. Or i'll start a huge mess between him and i.