I think it's nice to let her talk about the wedding BUT time limit it, and try not to make things worse by being so polite that she isn't given the opportunity to realise she's droning on about it too much. Or, in other words, limit the time she has available to bore you (let's be honest, that's what she's doing). So don't answer the phone to her; if you're in a group, make sure you don't sit next to her; make excuses if she wants to meet up (have a list handy!) and distract her whenever possible. You don't have to listen endlessly - just give her (say) 20 minutes, and then make sure you can go on to something-else. If she persists, then you'll have to put more space between you until after the wedding (when, of course, she'll want to discuss every detail of what happened !)