Ignorant people

I am so furious and upset at this point in time that I am not sure what I am capable of. I was told last evening that a fellow co-worker has been saying nasty things about me. I can deal with that. I believe in Karma. What I can't deal with is when she brings my Autistic daughter into this and calls her retarded and blames me for that. Says I don't spend enough time with her. I am just so furious! What right does this person have to say such nasty things. I have never done anything to my knowledge to warrant such a ficious attack. I am torn between letting it go and confronting her. I am just afraid that I will do something that I regret if I have to be near her, and I do tomorrow for an hour of my shift. I am so furious I am shaking and crying at the same time. I have a meeting today with the store manager and I am going to hold nothing back. Karma be damned at this point in time!!