If she valued the friendship, she'd of told you well in advance.
And she can't expect to just show up out of the blue and be taken in with open arms.
If you can start getting along again (finding common interests, etc), that's fine, but if being friends and chatting doesn't feel natural (ie, you have to really try to make things work), then perhaps you've moved on and it's better that way.
I had a similar situation happen to me once. I just didn't think it was right due to the awkwardness and such, so we just stopped talking (for good that time).