Interesting thread, very apt to being an indie as well.
The truth is that when you don't have money to make films, then goodwill is what we trade in. And although she's messed you about, if you can put that to one side and think "This woman may know someone I'm going to need at some point in the future to make a project happen" then treating her well, especially when she's messing you about is really to your benefit.
The other thing is, in this business the only thing of any value you own is your reputation. If you don't help her after promising you her that you would, even though she's been in the wrong, she's going to bad mouth you. Again, you never know when that is going to close a door that could have been open to you.
The truth is, the more she messes you about the more mellow you should be about it, because that increases her indebtedness. Trust me on this one, six degrees of separation is a reality, everyone you deal with is important.