Friend, or not to friend?

I got a message from someone on Classmates.com and I'm not sure how to deal with it. This person was my best friend from 7th grade until just a couple years ago. For reasons that I don't want to go into, we parted company. I thought it was the right decision at the time, but now I have mixed feelings on the subject. I feel splitting was a good thing, but I also miss her. She was perhaps the only person I have ever been friends with (besides my husband) that understood and perhaps exceeded my level of crazy. I don't know how to handle this situation. I sent a message containing my email address in reply- I figure that's safe enough, I can always just ignore the messages if I want to. Do I want to try being friends with her again? Is she different? Am I? Would it work? Arrgh!!