Yeah that really sucks .... I really don't believe she had any right to play around with your anticipation and then ultimately anxiety because that's really unfair on you. An indicator should not have been given in the interview then if there was some inkling that there may have been a change of mind because that's just beating you around the bush down a dead end trail to nothing. I really can't think of anything else other than perhaps they interviewed someone else / people higher up in the organisation chose someone else and maybe she wasn't supposed to have said that to you?

I really don't know.

Either way I just wanted to show you support on your post because it's not right at all what this company has done to you