I hate my husbands sister in law

Jessie
To start off she is a pathological liar. She honestly can you a story that changes 4 different times. I mean massively changes but she has gone to far. Today we had my daughters second birthday party. Everything seemed to be fine no problems. 2 hours later the sister in law and I go for a mile walk with my daughter. She tells me our mutual friend who was at the party had text her. She said the text was her asking if my husband and I beat our daughter.  Me being me I need to know both sides of the story before accusing someone of something. So I sent our friend a text stating this is a weird question but I need to know the truth. Sister in law told me that you had text her asking if we abuse our daughter. I know this is not true but I need to clear the air. Can you please verify this for me? ( note This friend is very blunt and the accusation does not sound like her at all.) she text me back saying absolutely not true then called me and told the text se recieved from her was stating that we beat her that's why she so well mannered. I couldn't believe what I was hearing. I called my father in law and explained the situation he sees us everyday he can't believe it either. 
Little background. My daughter is a very observant silent well behaved child when company is around or in public. She follows being asked to sit down and eat all the normal things you ask a child to do to teach manners and etiquette. 
My question is do you think I should confront the sister in law by myself or have my husband and father in law there so there are no lies about what was said?
Edit:
She has been informed that she is not to come near my house or my daughter. If she continues to make false accusations we will report her. She should also forget that exist cause for us she does not exist. I don't know what her dumb problem is with me and I choose to not care.