Complicated relationship question?

my best friend is a girl. We are very close. We dated once when we were young but it was a silly thing and nothing happened this was in 9th grade. So four years later I just got out of a relationship 6months ago in hopes that we could re kindle. Shes dating this guy.who is....not for her he just always gets her upset, but she still sticks with him. Were going to be away next year so do I tell her how I feel and risk.losing our best friend relationship or no?