I've had this happen to me too. Best friends, closer than sisters. Suddenly dropped me, didn't answer calls, messages or texts and then even refused to come to the phone, I heard her whisper "I'm not here!" to her parents on the phone when I once called there knowing she was visiting. We had never fallen out. There was no reason for the dumping.
I moved on. She kept my DM and DSis on her FB friend's list but not me (nosiness presumably). Years later I got a birthday text to which I replied, "Thanks. Who's this?" Of course I knew. She apologised for losing contact but didn't say why other than how we had drifted apart. I replied politely and we spoke for a few days then poof! Gone again.
Another year later I was contacted again as if nothing happened. I played along, never really getting a satisfactory explanation and again, POOF! Gone again. No replies.
9 months later she sent me an FB request and message. I replied, we caught up a little for a few weeks and like a magicians's handkerchief, she disappeared again.
Another year or so later she pulled that shit again.
These days it's a betting game between DH and I on how many days she will take to drop me again, I only respond merely for our amusement. I have no interest in her friendship. It does hurt but fuck that bitch.
OP, if you don't want her in your life then definitely tell her you're sorry that she would rather block and ignore you than see you happy and as such, of course, her coming to your wedding couldn't be any more of an insult.