2sweetangels There is no way I would have any kind of relationship with someone who LIED and said I abused my kids! I would call a lawyer and see what can be done about bringing legal charges of slander against this woman. If she is doing this and getting away with it there is no knowing where it may lead to.
She may decide she has a right to your girls and then only God knows what she would do. This would really scare me. If you can't afford a lawyer call legal services. You should get all this documented by a professional. If she somehow managed to convince the child services you were negligent (like you said one of the girls falls down and has a bruise, she might LIE and say she saw you hit her!) I shudder to think what would happen!
I don't mean to sound so paranoid, but that she would call child services and lie about you abusing your daughters is just WAY beyond the usual inlaw wierdness. I can't believe anyone would do that. Please do something concrete to safeguard your family from this vindictive and horrible woman.