Help!!

I really like this guy, I flirt with him, a lot. And I don't know if hes flirting back
how would I know? also, I've liked this guy for going on 3 years now.. should
tell him I like him? or would it ruin our friend ship? Also My best friend,
in the...

whole world started flirting with him and then asked him out
they dated for about 5 months then broke up.. Should I be friends with her still
because she stole the guy I really like?

be her friend just tell her that you really need some space and she would under stand your feeling if it were her it happend to so I say go fo it tell him how you feel it cant hert