What should i do? me and my gf havebeen 2gether for 4 yrs, we are kinda taking time off to try and work it out

several months ago she had moved out because we werent getting along after 4 days she wanted back now the so called "friend"she moved with is a bad influence she into partying andgoing out she would always use my gf to go out and think of her on the spot nvr in advance, not once did she talk to my gf about our relshp how a friend should do with frnds so after my gf tells this "friend" im moving back with him she stopped calling my gf deleted her as a friend on myspace and who knows what she told their circle of "friends" now that we are seperated this girl is back in her life after 5 months im sure my gf called her which she says no she called me now my gf is doing small favors while she is out of town gf doenst want to hear my opinion about her and tells me to mind my own bus. im sure this girl knows we are split and wants a new party buddy it makes me feel that my gf is choosing her over me even though she wants us to work out our relatshp. this girl is bad news gfs fam. dislikes her