Parents Writing Horrible Emails?

It sounds like to me that you are a good business woman and she is simply unhappy because she is out the money. If you have the paperwork then yo have done nothing wrong. Most likely she did not plan properly and thought if she bullied you that she would get her way. As hard as it will probably be I would ignore her. Hopefully you live in an area where it will not be detrimental to your business. She is behaving like a child.