Feeling scared to go back to work tommorrow, did I do the right thing?

You must sit down with your boss and in no uncertain terms describe all you have written here. This woman is a real haunt isn't she. She thought she could boos you around and, let's face it, you let things go to long and she got comfortable making you do her bidding under the guise of your "helping out." Explain to your boss that you are a team player but she is taking major advantage and she is starting to say things which may even have a threatening air about them.