Slander: Accused of Attempts to Harm a Child

My question involves defamation in the state of: California

I am being accused by a woman of attempting to kidnap her minor child and then harm said child. She has been spreading these rumors relentlessly to the point that I am unable to be any part of my local neighborhood children's groups

I also noticed that I was being thrown out of parenting groups on social media and suspected she was spreading rumors but had no idea what they were. A neighbor "did me a favor today" and told me that she was telling people that she was "afraid of me" and that I had threatened to kidnap and hurt her minor child. People are avoiding me without even hearing my side of the story and I want to put a stop to this. This neighbor does not want to "get involved" but felt that I "needed to know". I know that this neighbor is telling the truth because this woman has previously stated to me that she finds me "threatening" and wants my husband to reassure her that she is no danger of physical or verbal abuse from me ! That led her to be blocked on social media by me and on my cell phone. I want to know if I can do anything about her viciousness which has ruined my name in my community and made me a social outcast.

Please advise.

Slander: Accused of Attempts to Harm a Child