How do you approach talking with a former enemy?

As a child, I had a best friend who was like a sister to me. Then we had a falling out, she got me suspended for something I didn’t do, and things just went spiraling out of control. We were mortal enemies after that.

That was in the 6th grade. I haven’t spoken to her since. I had the idea of seeing if she had a Facebook, and sure enough I found her.

I added her because I wanted to not only catch up but clear up some things from the past before we both go off to college.

I have no idea how to approach this. Does anyone have any tips so it isn’t extremely awkward/unproductive?