Perhaps she is actually pregnant, but not as far along as she says/it seems...so because she wanted to make a big announcement at the VMA's, she wore a prosthetic belly to exaggerate the pregnancy for effect? Then, because she got herself into this...she's going to continue faking it until she 'grows into it'?
Or maybe, they're using a surrogate/adopting for whatever reason and she's going to 'fake it'? Still, that's a very weird move.
If she is faking it, the only way I could see her winning people back is if she says (true or otherwise) that she can't have children and...em...ok, even then it's not really 'explainable'.