O.H.
Hold the fort. The back story doesn't even matter. And this is hard to follow. But my point is that YOU reached out to her TWICE to clear the air. She met with you the second time and now you get a wedding invite. Since YOU tried to make up with her, I think you should go to the wedding and if hubs doesn't want to, take a friend.
As far as you were supposed to be in the wedding and talked about it when you were young. Well, yeah, my cousins in CO whom I've only met ONCE when we were all about 12 said that we were going to be roommates and live up in the mountains of CO together. Well, I'm 46 and have not held them to that. I mean really?
So unless you were not sincere in trying to patch things up with her, you should go and show that you meant it. If you weren't and are unhappy you are not in the wedding, then send a card with some cash and call it a day. JMO. Good luck.