I'd have it out with her. Just be straight and honest...tell her you feel awkward about the invite because she appears to have changed toward you.
She'll either tell you what her problem is (in which case perfect time to sort it out and see if you can get back to how it was), tell you you're imagining it(tell her about the ignored texts etc cos you are obv not imagining it) or she will carry on her strop and tell you she doesn't want to go to your wedding anyway.
Either way, its gotta be better than worrying about it!