Bettyann, this is a really tough situation to be in. You are trying to be a good person, opening your home to this woman and her child...and are now being taken advantage of.
Somehow you need to tell this person, "it's not working," and that she has to leave. It's your home. Your space. You tried and that's all anyone can ask of you.
We can help you get ready for The Talk with her if you are uncomfortable with confrontation. But you will absolutely need to do it.
So I would start looking for ways to get centered and do things to take care of yourself right now. Really.
It will go better, the talk, when you feel calm and assertive.
Do what you know helps you - go out to eat with DH, play with your pets, paint or be creative, do yoga, go for a walk, take a bath, listen to your music in your own private world of headphones from your favorite spot. Get a pedicure. See a movie or go to the zoo. These are all things that help me. Think about things that don't annoy you for a few hours.
When you decide to talk, we will help you with it. Just don't wait too long. It will be best done soonish!