Closure. Oh, how I hate that word.
Personally, I think people,
male or female, who insist on confessing to someone who they know already has a significant other (childhood friends or not) are among the worst sorts of inconsiderate, selfish and self-centered individuals. They think only of themselves and do not consider or care what adverse affects their selfish actions might cause to the object of their affection, or to the significant other. They cause others to suffer emotional pain and distress just so they can feel good that they were able to express their feelings. What a bunch of horseshit.
@Kind_Nesz
Well, she must to deal with this somehow, sooner or later.
She can, in the common vernacular, "just suck it up." Just keep it to yourself. Go home and cry into your pillow until you can't cry anymore. Just don't be a self-centered asshole and confess just because you need "closure."