My Grandmother used to say "Never be sad that people show you who they really are. When you know who you're dealing with, you'll know how to deall." Or not deal with them, as the case may be. One of my favorites is "Ye shall know the tree by it's fruit." Seems that some of he disappointment & frustration you feel may be because you don't like rotten fruit. Frankly, even if she came back later and said you were right, I don't know how you'd get past her utter lack of character and questionable moral compass, seeing as how yours has remained intact.