I'm thing about confessing to my childhood best friend that I love her.
Do you think she knows how you feel?
No, I haven't even really been close to her for a few years
I can understand why you want to let your feelings be known to someone that you care about, but this is someone that you haven't seen for a while, so how can you be sure.  Inserting romance into a relationship will only make things awkward unless you can be sure that your friend has feelings for you in return.
I don't think it will. She did always care about me a lot.
If you think it won't affect your friendship then it's fine that you tell her how you feel. But you should know that it might make her feel awkward, and could potentially ruin the friendship.