I don't know if this will help, but I believe in karma and have found it works in mysterious ways. It's not always "You scratch my back and I'll scratch yours." Sometimes it's "You scratch my back and karma will send you someone to scratch yours." Or "You scratch my back and I'll rub your feet." Sometimes the person you do good for won't reciprocate in kind, but you will get reciprocation.
Example: I helped "Nancy" move. She is disabled. When I moved, she didn't offer the same toting and carrying help I gave her, because she can't. But she introduced me to her son's best friend, who did help. And she made a salad to go with the pizza I provided for the helpers.
A kind gesture to Person A will not necessarily get you the same kind gesture back from her. But because you have put your good karma out there, along will come Person B to give you just what you need. (e.g., you baby-sit Susie's kids but she can't watch yours because she has two jobs or a sick parent. But because you are kind to Susie, you have Judy in your life, who is frequently willing to watch your kids). Maybe the baking hints that have been posted in this thread are your karmic payback for your own generosity in sharing recipes.
Personally, I wouldn't drop cupcake lady as a friend over this. It's just a recipe. I understand that you are frustrated at the lack of a response, but I would just chalk it up to "people are funny about some things" and either let the friendship die a natural death, if that's what's meant to be with her move away, or accept the good things she does bring to your life, sans recipe sharing.