Ex friend??????

How does one tell when you are no longer friends with someone- There's this girl, i am or used to be friends with, But she got this other friend, Were calling her c for the sake of this blog, And The old friend is E so E meets C And we just started talking less, and another girl in our friend group, D also hasnt heard from her, And neither has L Aka My cousin, So none of the friend group has heard from her after a good month of her knowing C. So are we still friends or are we just people she used to know now- Im so confused. The rest of the friend group is still in contact tho