Complex sentence: Cora says she is there to apologize and make things right and wants to see Regina happy by finding her the love that Tinker Bell spoke of, but Regina, having been upset with Tinker Bell previously, says she'll believe it when she sees it.
Split into simpler sentences: Cora says she is there to apologize and make things right, and that she wants to see Regina happy by finding her the love that Tinker Bell spoke of. But Regina, having been upset with Tinker Bell previously, says she'll believe it when she sees it.