Dianne - I'm so sorry you're going through this.
Deb is *brilliant* and exactly on point. The MIL is feeling insecure and her only way of getting "her lover back" is to drive you away. She's obviously making up lies.
So the key is to first take a deep breath, and realize she's doing this because she's scared. The love of her life has been "stolen" from her (in her mind) and she desperately wants him back. It's very sad that her own life is so insecure that this is what she feels she has to do. Imagine her as a really frightened 2 year old child. She says wild things out of her fear and pain. She'll say anything. You don't take a 2 year old seriously when she screams "I hate you!" I don't mean you should condescend to your MIL, but that you should have compassion.
That being said, being compassionate does not mean you let yourself be a doormat. You need to be gentle but firm. Deb's idea is AWESOME. Nod and agree that a refreshing spa visit would be PERFECT to cheer you up, to get you a fresh haircut and a glowing complexion! That would be just what she wants! Ask her for recommendations and hint that you would be happy to get it as your Easter present